diff --git a/.rubocop.yml b/.rubocop.yml
index 8a0c55d5d4..9b5044a6fc 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -77,6 +77,12 @@ Layout/SpaceBeforeFirstArg:
 Style/MethodDefParentheses:
   Enabled: true
 
+Style/FrozenStringLiteralComment:
+  Enabled: true
+  EnforcedStyle: always
+  Include:
+    - 'activesupport/**/*'
+
 # Use `foo {}` not `foo{}`.
 Layout/SpaceBeforeBlockBraces:
   Enabled: true
diff --git a/activesupport/Rakefile b/activesupport/Rakefile
index 2e1c50cc3d..8691a34035 100644
--- a/activesupport/Rakefile
+++ b/activesupport/Rakefile
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "rake/testtask"
 
 task default: :test
diff --git a/activesupport/activesupport.gemspec b/activesupport/activesupport.gemspec
index 16e912694c..4470de7ec1 100644
--- a/activesupport/activesupport.gemspec
+++ b/activesupport/activesupport.gemspec
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 version = File.read(File.expand_path("../RAILS_VERSION", __dir__)).strip
 
 Gem::Specification.new do |s|
diff --git a/activesupport/bin/generate_tables b/activesupport/bin/generate_tables
index 6f62593f14..18199b2171 100755
--- a/activesupport/bin/generate_tables
+++ b/activesupport/bin/generate_tables
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 
 begin
   $:.unshift(File.expand_path("../lib", __dir__))
diff --git a/activesupport/bin/test b/activesupport/bin/test
index 470ce93f10..c53377cc97 100755
--- a/activesupport/bin/test
+++ b/activesupport/bin/test
@@ -1,4 +1,5 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
 
 COMPONENT_ROOT = File.expand_path("..", __dir__)
 require_relative "../../tools/test"
diff --git a/activesupport/lib/active_support.rb b/activesupport/lib/active_support.rb
index 7302841075..65e903aeb9 100644
--- a/activesupport/lib/active_support.rb
+++ b/activesupport/lib/active_support.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 #--
 # Copyright (c) 2005-2017 David Heinemeier Hansson
 #
diff --git a/activesupport/lib/active_support/all.rb b/activesupport/lib/active_support/all.rb
index 413314167d..89f5d2b258 100644
--- a/activesupport/lib/active_support/all.rb
+++ b/activesupport/lib/active_support/all.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "active_support"
 require_relative "time"
 require_relative "core_ext"
diff --git a/activesupport/lib/active_support/array_inquirer.rb b/activesupport/lib/active_support/array_inquirer.rb
index befa1746c6..6dad208e43 100644
--- a/activesupport/lib/active_support/array_inquirer.rb
+++ b/activesupport/lib/active_support/array_inquirer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   # Wrapping an array in an +ArrayInquirer+ gives a friendlier way to check
   # its string-like contents:
diff --git a/activesupport/lib/active_support/backtrace_cleaner.rb b/activesupport/lib/active_support/backtrace_cleaner.rb
index e47c90597f..1ffa2c05a2 100644
--- a/activesupport/lib/active_support/backtrace_cleaner.rb
+++ b/activesupport/lib/active_support/backtrace_cleaner.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   # Backtraces often include many lines that are not relevant for the context
   # under review. This makes it hard to find the signal amongst the backtrace
diff --git a/activesupport/lib/active_support/benchmarkable.rb b/activesupport/lib/active_support/benchmarkable.rb
index 74e39c74e1..a201b43fdc 100644
--- a/activesupport/lib/active_support/benchmarkable.rb
+++ b/activesupport/lib/active_support/benchmarkable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "core_ext/benchmark"
 require_relative "core_ext/hash/keys"
 
diff --git a/activesupport/lib/active_support/builder.rb b/activesupport/lib/active_support/builder.rb
index 0f010c5d96..a7582a4f00 100644
--- a/activesupport/lib/active_support/builder.rb
+++ b/activesupport/lib/active_support/builder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 begin
   require "builder"
 rescue LoadError => e
diff --git a/activesupport/lib/active_support/cache.rb b/activesupport/lib/active_support/cache.rb
index f706f8ecf7..2ced73a0a6 100644
--- a/activesupport/lib/active_support/cache.rb
+++ b/activesupport/lib/active_support/cache.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "zlib"
 require_relative "core_ext/array/extract_options"
 require_relative "core_ext/array/wrap"
diff --git a/activesupport/lib/active_support/cache/file_store.rb b/activesupport/lib/active_support/cache/file_store.rb
index bb65da2723..87182e0254 100644
--- a/activesupport/lib/active_support/cache/file_store.rb
+++ b/activesupport/lib/active_support/cache/file_store.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../core_ext/marshal"
 require_relative "../core_ext/file/atomic"
 require_relative "../core_ext/string/conversions"
diff --git a/activesupport/lib/active_support/cache/mem_cache_store.rb b/activesupport/lib/active_support/cache/mem_cache_store.rb
index 7efe6fe3bf..de05dde8d4 100644
--- a/activesupport/lib/active_support/cache/mem_cache_store.rb
+++ b/activesupport/lib/active_support/cache/mem_cache_store.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 begin
   require "dalli"
 rescue LoadError => e
diff --git a/activesupport/lib/active_support/cache/memory_store.rb b/activesupport/lib/active_support/cache/memory_store.rb
index 56fe1457d0..e1fee72595 100644
--- a/activesupport/lib/active_support/cache/memory_store.rb
+++ b/activesupport/lib/active_support/cache/memory_store.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "monitor"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/cache/null_store.rb b/activesupport/lib/active_support/cache/null_store.rb
index 550659fc56..10ffbb84ea 100644
--- a/activesupport/lib/active_support/cache/null_store.rb
+++ b/activesupport/lib/active_support/cache/null_store.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module Cache
     # A cache store implementation which doesn't actually store anything. Useful in
diff --git a/activesupport/lib/active_support/cache/strategy/local_cache.rb b/activesupport/lib/active_support/cache/strategy/local_cache.rb
index 2e7e5af0e3..f3b65bcdef 100644
--- a/activesupport/lib/active_support/cache/strategy/local_cache.rb
+++ b/activesupport/lib/active_support/cache/strategy/local_cache.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../core_ext/object/duplicable"
 require_relative "../../core_ext/string/inflections"
 require_relative "../../per_thread_registry"
diff --git a/activesupport/lib/active_support/cache/strategy/local_cache_middleware.rb b/activesupport/lib/active_support/cache/strategy/local_cache_middleware.rb
index 4c3679e4bf..a53e268a92 100644
--- a/activesupport/lib/active_support/cache/strategy/local_cache_middleware.rb
+++ b/activesupport/lib/active_support/cache/strategy/local_cache_middleware.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "rack/body_proxy"
 require "rack/utils"
 
diff --git a/activesupport/lib/active_support/callbacks.rb b/activesupport/lib/active_support/callbacks.rb
index 34d62ec3a9..5cf8dbea90 100644
--- a/activesupport/lib/active_support/callbacks.rb
+++ b/activesupport/lib/active_support/callbacks.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "concern"
 require_relative "descendants_tracker"
 require_relative "core_ext/array/extract_options"
diff --git a/activesupport/lib/active_support/concern.rb b/activesupport/lib/active_support/concern.rb
index 0403eb70ca..f1dcda7dfa 100644
--- a/activesupport/lib/active_support/concern.rb
+++ b/activesupport/lib/active_support/concern.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   # A typical module looks like this:
   #
diff --git a/activesupport/lib/active_support/concurrency/share_lock.rb b/activesupport/lib/active_support/concurrency/share_lock.rb
index 4318523b07..060b16f2d6 100644
--- a/activesupport/lib/active_support/concurrency/share_lock.rb
+++ b/activesupport/lib/active_support/concurrency/share_lock.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "thread"
 require "monitor"
 
diff --git a/activesupport/lib/active_support/configurable.rb b/activesupport/lib/active_support/configurable.rb
index ebe4055f91..490925f37e 100644
--- a/activesupport/lib/active_support/configurable.rb
+++ b/activesupport/lib/active_support/configurable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "concern"
 require_relative "ordered_options"
 require_relative "core_ext/array/extract_options"
diff --git a/activesupport/lib/active_support/core_ext.rb b/activesupport/lib/active_support/core_ext.rb
index 42e0acf66a..784cdc4a78 100644
--- a/activesupport/lib/active_support/core_ext.rb
+++ b/activesupport/lib/active_support/core_ext.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 Dir.glob(File.expand_path("core_ext/*.rb", __dir__)).each do |path|
   require path
 end
diff --git a/activesupport/lib/active_support/core_ext/array.rb b/activesupport/lib/active_support/core_ext/array.rb
index 3536c7f2bf..c2876785dc 100644
--- a/activesupport/lib/active_support/core_ext/array.rb
+++ b/activesupport/lib/active_support/core_ext/array.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "array/wrap"
 require_relative "array/access"
 require_relative "array/conversions"
diff --git a/activesupport/lib/active_support/core_ext/array/access.rb b/activesupport/lib/active_support/core_ext/array/access.rb
index fca33c9d69..b6e576ad29 100644
--- a/activesupport/lib/active_support/core_ext/array/access.rb
+++ b/activesupport/lib/active_support/core_ext/array/access.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Array
   # Returns the tail of the array from +position+.
   #
diff --git a/activesupport/lib/active_support/core_ext/array/conversions.rb b/activesupport/lib/active_support/core_ext/array/conversions.rb
index 57ad32483a..eeafde78a4 100644
--- a/activesupport/lib/active_support/core_ext/array/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/array/conversions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../xml_mini"
 require_relative "../hash/keys"
 require_relative "../string/inflections"
diff --git a/activesupport/lib/active_support/core_ext/array/extract_options.rb b/activesupport/lib/active_support/core_ext/array/extract_options.rb
index 9008a0df2a..8204d42caf 100644
--- a/activesupport/lib/active_support/core_ext/array/extract_options.rb
+++ b/activesupport/lib/active_support/core_ext/array/extract_options.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Hash
   # By default, only instances of Hash itself are extractable.
   # Subclasses of Hash may implement this method and return
diff --git a/activesupport/lib/active_support/core_ext/array/grouping.rb b/activesupport/lib/active_support/core_ext/array/grouping.rb
index 0d798e5c4e..706c576691 100644
--- a/activesupport/lib/active_support/core_ext/array/grouping.rb
+++ b/activesupport/lib/active_support/core_ext/array/grouping.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Array
   # Splits or iterates over the array in groups of size +number+,
   # padding any remaining slots with +fill_with+ unless it is +false+.
diff --git a/activesupport/lib/active_support/core_ext/array/inquiry.rb b/activesupport/lib/active_support/core_ext/array/inquiry.rb
index c46b01baf0..b8a1bbdbc7 100644
--- a/activesupport/lib/active_support/core_ext/array/inquiry.rb
+++ b/activesupport/lib/active_support/core_ext/array/inquiry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../array_inquirer"
 
 class Array
diff --git a/activesupport/lib/active_support/core_ext/array/prepend_and_append.rb b/activesupport/lib/active_support/core_ext/array/prepend_and_append.rb
index 88a34128c9..2dd1547765 100644
--- a/activesupport/lib/active_support/core_ext/array/prepend_and_append.rb
+++ b/activesupport/lib/active_support/core_ext/array/prepend_and_append.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Array
   # The human way of thinking about adding stuff to the end of a list is with append.
   alias_method :append,  :push unless [].respond_to?(:append)
diff --git a/activesupport/lib/active_support/core_ext/array/wrap.rb b/activesupport/lib/active_support/core_ext/array/wrap.rb
index b611d34c27..adb25718e4 100644
--- a/activesupport/lib/active_support/core_ext/array/wrap.rb
+++ b/activesupport/lib/active_support/core_ext/array/wrap.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Array
   # Wraps its argument in an array unless it is already an array (or array-like).
   #
diff --git a/activesupport/lib/active_support/core_ext/benchmark.rb b/activesupport/lib/active_support/core_ext/benchmark.rb
index 2300953860..2db6e5f1c5 100644
--- a/activesupport/lib/active_support/core_ext/benchmark.rb
+++ b/activesupport/lib/active_support/core_ext/benchmark.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "benchmark"
 
 class << Benchmark
diff --git a/activesupport/lib/active_support/core_ext/big_decimal.rb b/activesupport/lib/active_support/core_ext/big_decimal.rb
index 7e396cac3c..fd860f6fbd 100644
--- a/activesupport/lib/active_support/core_ext/big_decimal.rb
+++ b/activesupport/lib/active_support/core_ext/big_decimal.rb
@@ -1 +1,2 @@
+# frozen_string_literal: true
 require_relative "big_decimal/conversions"
diff --git a/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb b/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb
index decd4e1699..1729f00530 100644
--- a/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/big_decimal/conversions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "bigdecimal"
 require "bigdecimal/util"
 
diff --git a/activesupport/lib/active_support/core_ext/class.rb b/activesupport/lib/active_support/core_ext/class.rb
index 66dd1c939a..882102831f 100644
--- a/activesupport/lib/active_support/core_ext/class.rb
+++ b/activesupport/lib/active_support/core_ext/class.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 require_relative "class/attribute"
 require_relative "class/subclasses"
diff --git a/activesupport/lib/active_support/core_ext/class/attribute.rb b/activesupport/lib/active_support/core_ext/class/attribute.rb
index 26b826b39b..a6da65e96d 100644
--- a/activesupport/lib/active_support/core_ext/class/attribute.rb
+++ b/activesupport/lib/active_support/core_ext/class/attribute.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../kernel/singleton_class"
 require_relative "../module/remove_method"
 require_relative "../array/extract_options"
diff --git a/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb b/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb
index eebf2e294a..0345478c59 100644
--- a/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb
+++ b/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # cattr_* became mattr_* aliases in 7dfbd91b0780fbd6a1dd9bfbc176e10894871d2d,
 # but we keep this around for libraries that directly require it knowing they
 # want cattr_*. No need to deprecate.
diff --git a/activesupport/lib/active_support/core_ext/class/subclasses.rb b/activesupport/lib/active_support/core_ext/class/subclasses.rb
index 545ad7fb3e..ce7b422cfb 100644
--- a/activesupport/lib/active_support/core_ext/class/subclasses.rb
+++ b/activesupport/lib/active_support/core_ext/class/subclasses.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../module/anonymous"
 require_relative "../module/reachable"
 
diff --git a/activesupport/lib/active_support/core_ext/date.rb b/activesupport/lib/active_support/core_ext/date.rb
index aba72c732f..88bae739b6 100644
--- a/activesupport/lib/active_support/core_ext/date.rb
+++ b/activesupport/lib/active_support/core_ext/date.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "date/acts_like"
 require_relative "date/blank"
 require_relative "date/calculations"
diff --git a/activesupport/lib/active_support/core_ext/date/acts_like.rb b/activesupport/lib/active_support/core_ext/date/acts_like.rb
index dfea3e3f09..c8ab7b5241 100644
--- a/activesupport/lib/active_support/core_ext/date/acts_like.rb
+++ b/activesupport/lib/active_support/core_ext/date/acts_like.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../object/acts_like"
 
 class Date
diff --git a/activesupport/lib/active_support/core_ext/date/blank.rb b/activesupport/lib/active_support/core_ext/date/blank.rb
index edd2847126..a28e726902 100644
--- a/activesupport/lib/active_support/core_ext/date/blank.rb
+++ b/activesupport/lib/active_support/core_ext/date/blank.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "date"
 
 class Date #:nodoc:
diff --git a/activesupport/lib/active_support/core_ext/date/calculations.rb b/activesupport/lib/active_support/core_ext/date/calculations.rb
index 24d3721d48..d0ac71210a 100644
--- a/activesupport/lib/active_support/core_ext/date/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date/calculations.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "date"
 require_relative "../../duration"
 require_relative "../object/acts_like"
diff --git a/activesupport/lib/active_support/core_ext/date/conversions.rb b/activesupport/lib/active_support/core_ext/date/conversions.rb
index 7971d39fb7..6c493dc2c8 100644
--- a/activesupport/lib/active_support/core_ext/date/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/date/conversions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "date"
 require_relative "../../inflector/methods"
 require_relative "zones"
diff --git a/activesupport/lib/active_support/core_ext/date/zones.rb b/activesupport/lib/active_support/core_ext/date/zones.rb
index d94c7bcfc2..f9bb6f733b 100644
--- a/activesupport/lib/active_support/core_ext/date/zones.rb
+++ b/activesupport/lib/active_support/core_ext/date/zones.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "date"
 require_relative "../date_and_time/zones"
 
diff --git a/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb b/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb
index cf01a4542f..4e93851259 100644
--- a/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date_and_time/calculations.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../object/try"
 
 module DateAndTime
diff --git a/activesupport/lib/active_support/core_ext/date_and_time/compatibility.rb b/activesupport/lib/active_support/core_ext/date_and_time/compatibility.rb
index bb9908df61..ffb1cbd6e5 100644
--- a/activesupport/lib/active_support/core_ext/date_and_time/compatibility.rb
+++ b/activesupport/lib/active_support/core_ext/date_and_time/compatibility.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../module/attribute_accessors"
 
 module DateAndTime
diff --git a/activesupport/lib/active_support/core_ext/date_and_time/zones.rb b/activesupport/lib/active_support/core_ext/date_and_time/zones.rb
index edd724f1d0..4cc94d4ece 100644
--- a/activesupport/lib/active_support/core_ext/date_and_time/zones.rb
+++ b/activesupport/lib/active_support/core_ext/date_and_time/zones.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module DateAndTime
   module Zones
     # Returns the simultaneous time in <tt>Time.zone</tt> if a zone is given or
diff --git a/activesupport/lib/active_support/core_ext/date_time.rb b/activesupport/lib/active_support/core_ext/date_time.rb
index ce35026a71..fba37a5169 100644
--- a/activesupport/lib/active_support/core_ext/date_time.rb
+++ b/activesupport/lib/active_support/core_ext/date_time.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "date_time/acts_like"
 require_relative "date_time/blank"
 require_relative "date_time/calculations"
diff --git a/activesupport/lib/active_support/core_ext/date_time/acts_like.rb b/activesupport/lib/active_support/core_ext/date_time/acts_like.rb
index f0356ee6a0..74a2758830 100644
--- a/activesupport/lib/active_support/core_ext/date_time/acts_like.rb
+++ b/activesupport/lib/active_support/core_ext/date_time/acts_like.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "date"
 require_relative "../object/acts_like"
 
diff --git a/activesupport/lib/active_support/core_ext/date_time/blank.rb b/activesupport/lib/active_support/core_ext/date_time/blank.rb
index b475fd926d..874c7554a3 100644
--- a/activesupport/lib/active_support/core_ext/date_time/blank.rb
+++ b/activesupport/lib/active_support/core_ext/date_time/blank.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "date"
 
 class DateTime #:nodoc:
diff --git a/activesupport/lib/active_support/core_ext/date_time/calculations.rb b/activesupport/lib/active_support/core_ext/date_time/calculations.rb
index 7a9eb8c266..91289175ed 100644
--- a/activesupport/lib/active_support/core_ext/date_time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/date_time/calculations.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "date"
 
 class DateTime
diff --git a/activesupport/lib/active_support/core_ext/date_time/compatibility.rb b/activesupport/lib/active_support/core_ext/date_time/compatibility.rb
index fe255c087f..e2bb02d855 100644
--- a/activesupport/lib/active_support/core_ext/date_time/compatibility.rb
+++ b/activesupport/lib/active_support/core_ext/date_time/compatibility.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../date_and_time/compatibility"
 require_relative "../module/remove_method"
 
diff --git a/activesupport/lib/active_support/core_ext/date_time/conversions.rb b/activesupport/lib/active_support/core_ext/date_time/conversions.rb
index 36bfd28f31..2a35f9dbfb 100644
--- a/activesupport/lib/active_support/core_ext/date_time/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/date_time/conversions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "date"
 require_relative "../../inflector/methods"
 require_relative "../time/conversions"
diff --git a/activesupport/lib/active_support/core_ext/digest/uuid.rb b/activesupport/lib/active_support/core_ext/digest/uuid.rb
index e6d60e3267..26a300feb6 100644
--- a/activesupport/lib/active_support/core_ext/digest/uuid.rb
+++ b/activesupport/lib/active_support/core_ext/digest/uuid.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "securerandom"
 
 module Digest
diff --git a/activesupport/lib/active_support/core_ext/enumerable.rb b/activesupport/lib/active_support/core_ext/enumerable.rb
index 3a4ae6cb8b..a744b78e1c 100644
--- a/activesupport/lib/active_support/core_ext/enumerable.rb
+++ b/activesupport/lib/active_support/core_ext/enumerable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Enumerable
   # Enumerable#sum was added in Ruby 2.4, but it only works with Numeric elements
   # when we omit an identity.
diff --git a/activesupport/lib/active_support/core_ext/file.rb b/activesupport/lib/active_support/core_ext/file.rb
index ea3267f5da..9de5fbb63c 100644
--- a/activesupport/lib/active_support/core_ext/file.rb
+++ b/activesupport/lib/active_support/core_ext/file.rb
@@ -1 +1,2 @@
+# frozen_string_literal: true
 require_relative "file/atomic"
diff --git a/activesupport/lib/active_support/core_ext/file/atomic.rb b/activesupport/lib/active_support/core_ext/file/atomic.rb
index 8d6c0d3685..5b30e93357 100644
--- a/activesupport/lib/active_support/core_ext/file/atomic.rb
+++ b/activesupport/lib/active_support/core_ext/file/atomic.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "fileutils"
 
 class File
diff --git a/activesupport/lib/active_support/core_ext/hash.rb b/activesupport/lib/active_support/core_ext/hash.rb
index 6122ac57ba..24b6adeb5f 100644
--- a/activesupport/lib/active_support/core_ext/hash.rb
+++ b/activesupport/lib/active_support/core_ext/hash.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "hash/compact"
 require_relative "hash/conversions"
 require_relative "hash/deep_merge"
diff --git a/activesupport/lib/active_support/core_ext/hash/compact.rb b/activesupport/lib/active_support/core_ext/hash/compact.rb
index e357284be0..ddccbe7d16 100644
--- a/activesupport/lib/active_support/core_ext/hash/compact.rb
+++ b/activesupport/lib/active_support/core_ext/hash/compact.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Hash
   unless Hash.instance_methods(false).include?(:compact)
     # Returns a hash with non +nil+ values.
diff --git a/activesupport/lib/active_support/core_ext/hash/conversions.rb b/activesupport/lib/active_support/core_ext/hash/conversions.rb
index 713711e16a..193004608a 100644
--- a/activesupport/lib/active_support/core_ext/hash/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/hash/conversions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../xml_mini"
 require_relative "../../time"
 require_relative "../object/blank"
diff --git a/activesupport/lib/active_support/core_ext/hash/deep_merge.rb b/activesupport/lib/active_support/core_ext/hash/deep_merge.rb
index 9c9faf67ea..1c6627a597 100644
--- a/activesupport/lib/active_support/core_ext/hash/deep_merge.rb
+++ b/activesupport/lib/active_support/core_ext/hash/deep_merge.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Hash
   # Returns a new hash with +self+ and +other_hash+ merged recursively.
   #
diff --git a/activesupport/lib/active_support/core_ext/hash/except.rb b/activesupport/lib/active_support/core_ext/hash/except.rb
index 2f6d38c1f6..e31c7c61e4 100644
--- a/activesupport/lib/active_support/core_ext/hash/except.rb
+++ b/activesupport/lib/active_support/core_ext/hash/except.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Hash
   # Returns a hash that includes everything except given keys.
   #   hash = { a: true, b: false, c: nil }
diff --git a/activesupport/lib/active_support/core_ext/hash/indifferent_access.rb b/activesupport/lib/active_support/core_ext/hash/indifferent_access.rb
index 4b7fe34cc9..7727f0751e 100644
--- a/activesupport/lib/active_support/core_ext/hash/indifferent_access.rb
+++ b/activesupport/lib/active_support/core_ext/hash/indifferent_access.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../hash_with_indifferent_access"
 
 class Hash
diff --git a/activesupport/lib/active_support/core_ext/hash/keys.rb b/activesupport/lib/active_support/core_ext/hash/keys.rb
index b7089357a8..b38ea9ba50 100644
--- a/activesupport/lib/active_support/core_ext/hash/keys.rb
+++ b/activesupport/lib/active_support/core_ext/hash/keys.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Hash
   # Returns a new hash with all keys converted using the +block+ operation.
   #
diff --git a/activesupport/lib/active_support/core_ext/hash/reverse_merge.rb b/activesupport/lib/active_support/core_ext/hash/reverse_merge.rb
index 061c959442..2055d06385 100644
--- a/activesupport/lib/active_support/core_ext/hash/reverse_merge.rb
+++ b/activesupport/lib/active_support/core_ext/hash/reverse_merge.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Hash
   # Merges the caller into +other_hash+. For example,
   #
diff --git a/activesupport/lib/active_support/core_ext/hash/slice.rb b/activesupport/lib/active_support/core_ext/hash/slice.rb
index 161b00dfb3..bd370931e4 100644
--- a/activesupport/lib/active_support/core_ext/hash/slice.rb
+++ b/activesupport/lib/active_support/core_ext/hash/slice.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Hash
   # Slices a hash to include only the given keys. Returns a hash containing
   # the given keys.
diff --git a/activesupport/lib/active_support/core_ext/hash/transform_values.rb b/activesupport/lib/active_support/core_ext/hash/transform_values.rb
index 2f693bff0c..b6e2734193 100644
--- a/activesupport/lib/active_support/core_ext/hash/transform_values.rb
+++ b/activesupport/lib/active_support/core_ext/hash/transform_values.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Hash
   # Returns a new hash with the results of running +block+ once for every value.
   # The keys are unchanged.
diff --git a/activesupport/lib/active_support/core_ext/integer.rb b/activesupport/lib/active_support/core_ext/integer.rb
index e7c1aae980..2042b5d311 100644
--- a/activesupport/lib/active_support/core_ext/integer.rb
+++ b/activesupport/lib/active_support/core_ext/integer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "integer/multiple"
 require_relative "integer/inflections"
 require_relative "integer/time"
diff --git a/activesupport/lib/active_support/core_ext/integer/inflections.rb b/activesupport/lib/active_support/core_ext/integer/inflections.rb
index 0b2ada8b22..de756446ba 100644
--- a/activesupport/lib/active_support/core_ext/integer/inflections.rb
+++ b/activesupport/lib/active_support/core_ext/integer/inflections.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../inflector"
 
 class Integer
diff --git a/activesupport/lib/active_support/core_ext/integer/multiple.rb b/activesupport/lib/active_support/core_ext/integer/multiple.rb
index c668c7c2eb..2e4d78e66c 100644
--- a/activesupport/lib/active_support/core_ext/integer/multiple.rb
+++ b/activesupport/lib/active_support/core_ext/integer/multiple.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Integer
   # Check whether the integer is evenly divisible by the argument.
   #
diff --git a/activesupport/lib/active_support/core_ext/integer/time.rb b/activesupport/lib/active_support/core_ext/integer/time.rb
index d5625dfd1c..583ef456f3 100644
--- a/activesupport/lib/active_support/core_ext/integer/time.rb
+++ b/activesupport/lib/active_support/core_ext/integer/time.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../duration"
 require_relative "../numeric/time"
 
diff --git a/activesupport/lib/active_support/core_ext/kernel.rb b/activesupport/lib/active_support/core_ext/kernel.rb
index 26142b107b..9ac0ba3749 100644
--- a/activesupport/lib/active_support/core_ext/kernel.rb
+++ b/activesupport/lib/active_support/core_ext/kernel.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "kernel/agnostics"
 require_relative "kernel/concern"
 require_relative "kernel/reporting"
diff --git a/activesupport/lib/active_support/core_ext/kernel/agnostics.rb b/activesupport/lib/active_support/core_ext/kernel/agnostics.rb
index 64837d87aa..84a48979c4 100644
--- a/activesupport/lib/active_support/core_ext/kernel/agnostics.rb
+++ b/activesupport/lib/active_support/core_ext/kernel/agnostics.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Object
   # Makes backticks behave (somewhat more) similarly on all platforms.
   # On win32 `nonexistent_command` raises Errno::ENOENT; on Unix, the
diff --git a/activesupport/lib/active_support/core_ext/kernel/concern.rb b/activesupport/lib/active_support/core_ext/kernel/concern.rb
index 535f0d21df..e6df8aa46e 100644
--- a/activesupport/lib/active_support/core_ext/kernel/concern.rb
+++ b/activesupport/lib/active_support/core_ext/kernel/concern.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../module/concerning"
 
 module Kernel
diff --git a/activesupport/lib/active_support/core_ext/kernel/reporting.rb b/activesupport/lib/active_support/core_ext/kernel/reporting.rb
index c02618d5f3..822efb5aae 100644
--- a/activesupport/lib/active_support/core_ext/kernel/reporting.rb
+++ b/activesupport/lib/active_support/core_ext/kernel/reporting.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Kernel
   module_function
 
diff --git a/activesupport/lib/active_support/core_ext/kernel/singleton_class.rb b/activesupport/lib/active_support/core_ext/kernel/singleton_class.rb
index 9bbf1bbd73..5f9c008f6e 100644
--- a/activesupport/lib/active_support/core_ext/kernel/singleton_class.rb
+++ b/activesupport/lib/active_support/core_ext/kernel/singleton_class.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Kernel
   # class_eval on an object acts like singleton_class.class_eval.
   def class_eval(*args, &block)
diff --git a/activesupport/lib/active_support/core_ext/load_error.rb b/activesupport/lib/active_support/core_ext/load_error.rb
index d273487010..55177efdaf 100644
--- a/activesupport/lib/active_support/core_ext/load_error.rb
+++ b/activesupport/lib/active_support/core_ext/load_error.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class LoadError
   REGEXPS = [
     /^no such file to load -- (.+)$/i,
diff --git a/activesupport/lib/active_support/core_ext/marshal.rb b/activesupport/lib/active_support/core_ext/marshal.rb
index bba2b3be2e..13b1d0cf95 100644
--- a/activesupport/lib/active_support/core_ext/marshal.rb
+++ b/activesupport/lib/active_support/core_ext/marshal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module MarshalWithAutoloading # :nodoc:
     def load(source, proc = nil)
diff --git a/activesupport/lib/active_support/core_ext/module.rb b/activesupport/lib/active_support/core_ext/module.rb
index 3ee394edd9..6c304292eb 100644
--- a/activesupport/lib/active_support/core_ext/module.rb
+++ b/activesupport/lib/active_support/core_ext/module.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "module/aliasing"
 require_relative "module/introspection"
 require_relative "module/anonymous"
diff --git a/activesupport/lib/active_support/core_ext/module/aliasing.rb b/activesupport/lib/active_support/core_ext/module/aliasing.rb
index c48bd3354a..62eb9e4c76 100644
--- a/activesupport/lib/active_support/core_ext/module/aliasing.rb
+++ b/activesupport/lib/active_support/core_ext/module/aliasing.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Module
   # Allows you to make aliases for attributes, which includes
   # getter, setter, and a predicate.
diff --git a/activesupport/lib/active_support/core_ext/module/anonymous.rb b/activesupport/lib/active_support/core_ext/module/anonymous.rb
index 510c9a5430..7d10240199 100644
--- a/activesupport/lib/active_support/core_ext/module/anonymous.rb
+++ b/activesupport/lib/active_support/core_ext/module/anonymous.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Module
   # A module may or may not have a name.
   #
diff --git a/activesupport/lib/active_support/core_ext/module/attr_internal.rb b/activesupport/lib/active_support/core_ext/module/attr_internal.rb
index 5081d5f7a3..8d37460dbc 100644
--- a/activesupport/lib/active_support/core_ext/module/attr_internal.rb
+++ b/activesupport/lib/active_support/core_ext/module/attr_internal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Module
   # Declares an attribute reader backed by an internally-named instance variable.
   def attr_internal_reader(*attrs)
diff --git a/activesupport/lib/active_support/core_ext/module/attribute_accessors.rb b/activesupport/lib/active_support/core_ext/module/attribute_accessors.rb
index e978bd41d6..430b1accbc 100644
--- a/activesupport/lib/active_support/core_ext/module/attribute_accessors.rb
+++ b/activesupport/lib/active_support/core_ext/module/attribute_accessors.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../array/extract_options"
 require_relative "../regexp"
 
diff --git a/activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb b/activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb
index 9ef834fa6f..bc5d4b6dda 100644
--- a/activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb
+++ b/activesupport/lib/active_support/core_ext/module/attribute_accessors_per_thread.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../array/extract_options"
 require_relative "../regexp"
 
diff --git a/activesupport/lib/active_support/core_ext/module/concerning.rb b/activesupport/lib/active_support/core_ext/module/concerning.rb
index eb821aba60..e4e49746b6 100644
--- a/activesupport/lib/active_support/core_ext/module/concerning.rb
+++ b/activesupport/lib/active_support/core_ext/module/concerning.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../concern"
 
 class Module
diff --git a/activesupport/lib/active_support/core_ext/module/delegation.rb b/activesupport/lib/active_support/core_ext/module/delegation.rb
index 04f34e553d..dc6906081c 100644
--- a/activesupport/lib/active_support/core_ext/module/delegation.rb
+++ b/activesupport/lib/active_support/core_ext/module/delegation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "set"
 require_relative "../regexp"
 
diff --git a/activesupport/lib/active_support/core_ext/module/deprecation.rb b/activesupport/lib/active_support/core_ext/module/deprecation.rb
index f3f2e7f5fc..98dfaad760 100644
--- a/activesupport/lib/active_support/core_ext/module/deprecation.rb
+++ b/activesupport/lib/active_support/core_ext/module/deprecation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Module
   #   deprecate :foo
   #   deprecate bar: 'message'
diff --git a/activesupport/lib/active_support/core_ext/module/introspection.rb b/activesupport/lib/active_support/core_ext/module/introspection.rb
index 4a7930792c..69122885ec 100644
--- a/activesupport/lib/active_support/core_ext/module/introspection.rb
+++ b/activesupport/lib/active_support/core_ext/module/introspection.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../inflector"
 
 class Module
diff --git a/activesupport/lib/active_support/core_ext/module/reachable.rb b/activesupport/lib/active_support/core_ext/module/reachable.rb
index 0f78999634..023894055f 100644
--- a/activesupport/lib/active_support/core_ext/module/reachable.rb
+++ b/activesupport/lib/active_support/core_ext/module/reachable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "anonymous"
 require_relative "../string/inflections"
 
diff --git a/activesupport/lib/active_support/core_ext/module/remove_method.rb b/activesupport/lib/active_support/core_ext/module/remove_method.rb
index d5ec16d68a..c17808b244 100644
--- a/activesupport/lib/active_support/core_ext/module/remove_method.rb
+++ b/activesupport/lib/active_support/core_ext/module/remove_method.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Module
   # Removes the named method, if it exists.
   def remove_possible_method(method)
diff --git a/activesupport/lib/active_support/core_ext/name_error.rb b/activesupport/lib/active_support/core_ext/name_error.rb
index 6b447d772b..1bcb6ded3c 100644
--- a/activesupport/lib/active_support/core_ext/name_error.rb
+++ b/activesupport/lib/active_support/core_ext/name_error.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class NameError
   # Extract the name of the missing constant from the exception message.
   #
diff --git a/activesupport/lib/active_support/core_ext/numeric.rb b/activesupport/lib/active_support/core_ext/numeric.rb
index e10d7708bd..6c407bc1ff 100644
--- a/activesupport/lib/active_support/core_ext/numeric.rb
+++ b/activesupport/lib/active_support/core_ext/numeric.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "numeric/bytes"
 require_relative "numeric/time"
 require_relative "numeric/inquiry"
diff --git a/activesupport/lib/active_support/core_ext/numeric/bytes.rb b/activesupport/lib/active_support/core_ext/numeric/bytes.rb
index dfbca32474..23e1e39dd8 100644
--- a/activesupport/lib/active_support/core_ext/numeric/bytes.rb
+++ b/activesupport/lib/active_support/core_ext/numeric/bytes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Numeric
   KILOBYTE = 1024
   MEGABYTE = KILOBYTE * 1024
diff --git a/activesupport/lib/active_support/core_ext/numeric/conversions.rb b/activesupport/lib/active_support/core_ext/numeric/conversions.rb
index 397e32ee8e..b8cff9aeb9 100644
--- a/activesupport/lib/active_support/core_ext/numeric/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/numeric/conversions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../big_decimal/conversions"
 require_relative "../../number_helper"
 require_relative "../module/deprecation"
diff --git a/activesupport/lib/active_support/core_ext/numeric/inquiry.rb b/activesupport/lib/active_support/core_ext/numeric/inquiry.rb
index ec79701189..baccf87848 100644
--- a/activesupport/lib/active_support/core_ext/numeric/inquiry.rb
+++ b/activesupport/lib/active_support/core_ext/numeric/inquiry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 unless 1.respond_to?(:positive?) # TODO: Remove this file when we drop support to ruby < 2.3
   class Numeric
     # Returns true if the number is positive.
diff --git a/activesupport/lib/active_support/core_ext/numeric/time.rb b/activesupport/lib/active_support/core_ext/numeric/time.rb
index cf002552fb..382a8cd162 100644
--- a/activesupport/lib/active_support/core_ext/numeric/time.rb
+++ b/activesupport/lib/active_support/core_ext/numeric/time.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../duration"
 require_relative "../time/calculations"
 require_relative "../time/acts_like"
diff --git a/activesupport/lib/active_support/core_ext/object.rb b/activesupport/lib/active_support/core_ext/object.rb
index 993cc6a059..cd350d5c45 100644
--- a/activesupport/lib/active_support/core_ext/object.rb
+++ b/activesupport/lib/active_support/core_ext/object.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "object/acts_like"
 require_relative "object/blank"
 require_relative "object/duplicable"
diff --git a/activesupport/lib/active_support/core_ext/object/acts_like.rb b/activesupport/lib/active_support/core_ext/object/acts_like.rb
index 3912cc5ace..b856e1ba16 100644
--- a/activesupport/lib/active_support/core_ext/object/acts_like.rb
+++ b/activesupport/lib/active_support/core_ext/object/acts_like.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Object
   # A duck-type assistant method. For example, Active Support extends Date
   # to define an <tt>acts_like_date?</tt> method, and extends Time to define
diff --git a/activesupport/lib/active_support/core_ext/object/blank.rb b/activesupport/lib/active_support/core_ext/object/blank.rb
index c37c2649d6..fd10e1bf72 100644
--- a/activesupport/lib/active_support/core_ext/object/blank.rb
+++ b/activesupport/lib/active_support/core_ext/object/blank.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../regexp"
 
 class Object
diff --git a/activesupport/lib/active_support/core_ext/object/conversions.rb b/activesupport/lib/active_support/core_ext/object/conversions.rb
index 9d3bdbc528..846e3a4fa7 100644
--- a/activesupport/lib/active_support/core_ext/object/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/object/conversions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "to_param"
 require_relative "to_query"
 require_relative "../array/conversions"
diff --git a/activesupport/lib/active_support/core_ext/object/deep_dup.rb b/activesupport/lib/active_support/core_ext/object/deep_dup.rb
index d966a29408..ac7537b500 100644
--- a/activesupport/lib/active_support/core_ext/object/deep_dup.rb
+++ b/activesupport/lib/active_support/core_ext/object/deep_dup.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "duplicable"
 
 class Object
diff --git a/activesupport/lib/active_support/core_ext/object/duplicable.rb b/activesupport/lib/active_support/core_ext/object/duplicable.rb
index b028df97ee..0838b1fb70 100644
--- a/activesupport/lib/active_support/core_ext/object/duplicable.rb
+++ b/activesupport/lib/active_support/core_ext/object/duplicable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 #--
 # Most objects are cloneable, but not all. For example you can't dup methods:
 #
diff --git a/activesupport/lib/active_support/core_ext/object/inclusion.rb b/activesupport/lib/active_support/core_ext/object/inclusion.rb
index 98bf820d36..525ddcb575 100644
--- a/activesupport/lib/active_support/core_ext/object/inclusion.rb
+++ b/activesupport/lib/active_support/core_ext/object/inclusion.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Object
   # Returns true if this object is included in the argument. Argument must be
   # any object which responds to +#include?+. Usage:
diff --git a/activesupport/lib/active_support/core_ext/object/instance_variables.rb b/activesupport/lib/active_support/core_ext/object/instance_variables.rb
index 593a7a4940..0a06125210 100644
--- a/activesupport/lib/active_support/core_ext/object/instance_variables.rb
+++ b/activesupport/lib/active_support/core_ext/object/instance_variables.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Object
   # Returns a hash with string keys that maps instance variable names without "@" to their
   # corresponding values.
diff --git a/activesupport/lib/active_support/core_ext/object/json.rb b/activesupport/lib/active_support/core_ext/object/json.rb
index d54373d5f2..3c8846029f 100644
--- a/activesupport/lib/active_support/core_ext/object/json.rb
+++ b/activesupport/lib/active_support/core_ext/object/json.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Hack to load json gem first so we can overwrite its to_json.
 require "json"
 require "bigdecimal"
diff --git a/activesupport/lib/active_support/core_ext/object/to_param.rb b/activesupport/lib/active_support/core_ext/object/to_param.rb
index d39727ce00..0b172829db 100644
--- a/activesupport/lib/active_support/core_ext/object/to_param.rb
+++ b/activesupport/lib/active_support/core_ext/object/to_param.rb
@@ -1 +1,2 @@
+# frozen_string_literal: true
 require_relative "to_query"
diff --git a/activesupport/lib/active_support/core_ext/object/to_query.rb b/activesupport/lib/active_support/core_ext/object/to_query.rb
index a3a3abacbb..f85e0eaa6f 100644
--- a/activesupport/lib/active_support/core_ext/object/to_query.rb
+++ b/activesupport/lib/active_support/core_ext/object/to_query.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cgi"
 
 class Object
diff --git a/activesupport/lib/active_support/core_ext/object/try.rb b/activesupport/lib/active_support/core_ext/object/try.rb
index b2be619b2d..952fba4541 100644
--- a/activesupport/lib/active_support/core_ext/object/try.rb
+++ b/activesupport/lib/active_support/core_ext/object/try.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "delegate"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/core_ext/object/with_options.rb b/activesupport/lib/active_support/core_ext/object/with_options.rb
index 68a8da25ff..22a0034d7d 100644
--- a/activesupport/lib/active_support/core_ext/object/with_options.rb
+++ b/activesupport/lib/active_support/core_ext/object/with_options.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../option_merger"
 
 class Object
diff --git a/activesupport/lib/active_support/core_ext/range.rb b/activesupport/lib/active_support/core_ext/range.rb
index 3e17780b76..db4c63380b 100644
--- a/activesupport/lib/active_support/core_ext/range.rb
+++ b/activesupport/lib/active_support/core_ext/range.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "range/conversions"
 require_relative "range/include_range"
 require_relative "range/overlaps"
diff --git a/activesupport/lib/active_support/core_ext/range/conversions.rb b/activesupport/lib/active_support/core_ext/range/conversions.rb
index 69ea046cb6..5038a15cdf 100644
--- a/activesupport/lib/active_support/core_ext/range/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/range/conversions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport::RangeWithFormat
   RANGE_FORMATS = {
     db: Proc.new { |start, stop| "BETWEEN '#{start.to_s(:db)}' AND '#{stop.to_s(:db)}'" }
diff --git a/activesupport/lib/active_support/core_ext/range/each.rb b/activesupport/lib/active_support/core_ext/range/each.rb
index dc6dad5ced..aeea8c867b 100644
--- a/activesupport/lib/active_support/core_ext/range/each.rb
+++ b/activesupport/lib/active_support/core_ext/range/each.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module EachTimeWithZone #:nodoc:
     def each(&block)
diff --git a/activesupport/lib/active_support/core_ext/range/include_range.rb b/activesupport/lib/active_support/core_ext/range/include_range.rb
index c69e1e3fb9..d307750a23 100644
--- a/activesupport/lib/active_support/core_ext/range/include_range.rb
+++ b/activesupport/lib/active_support/core_ext/range/include_range.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module IncludeWithRange #:nodoc:
     # Extends the default Range#include? to support range comparisons.
diff --git a/activesupport/lib/active_support/core_ext/range/overlaps.rb b/activesupport/lib/active_support/core_ext/range/overlaps.rb
index 603657c180..ecdfbd803b 100644
--- a/activesupport/lib/active_support/core_ext/range/overlaps.rb
+++ b/activesupport/lib/active_support/core_ext/range/overlaps.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Range
   # Compare two ranges and see if they overlap each other
   #  (1..5).overlaps?(4..6) # => true
diff --git a/activesupport/lib/active_support/core_ext/regexp.rb b/activesupport/lib/active_support/core_ext/regexp.rb
index d77d01bf42..23b337ba67 100644
--- a/activesupport/lib/active_support/core_ext/regexp.rb
+++ b/activesupport/lib/active_support/core_ext/regexp.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class Regexp #:nodoc:
   def multiline?
     options & MULTILINE == MULTILINE
diff --git a/activesupport/lib/active_support/core_ext/securerandom.rb b/activesupport/lib/active_support/core_ext/securerandom.rb
index a57685bea1..033ac356bd 100644
--- a/activesupport/lib/active_support/core_ext/securerandom.rb
+++ b/activesupport/lib/active_support/core_ext/securerandom.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "securerandom"
 
 module SecureRandom
diff --git a/activesupport/lib/active_support/core_ext/string.rb b/activesupport/lib/active_support/core_ext/string.rb
index b16b35144e..cefd82fa20 100644
--- a/activesupport/lib/active_support/core_ext/string.rb
+++ b/activesupport/lib/active_support/core_ext/string.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "string/conversions"
 require_relative "string/filters"
 require_relative "string/multibyte"
diff --git a/activesupport/lib/active_support/core_ext/string/access.rb b/activesupport/lib/active_support/core_ext/string/access.rb
index 6133826f37..11f4bf8052 100644
--- a/activesupport/lib/active_support/core_ext/string/access.rb
+++ b/activesupport/lib/active_support/core_ext/string/access.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class String
   # If you pass a single integer, returns a substring of one character at that
   # position. The first character of the string is at position 0, the next at
diff --git a/activesupport/lib/active_support/core_ext/string/behavior.rb b/activesupport/lib/active_support/core_ext/string/behavior.rb
index 710f1f4670..e63888991d 100644
--- a/activesupport/lib/active_support/core_ext/string/behavior.rb
+++ b/activesupport/lib/active_support/core_ext/string/behavior.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class String
   # Enables more predictable duck-typing on String-like classes. See <tt>Object#acts_like?</tt>.
   def acts_like_string?
diff --git a/activesupport/lib/active_support/core_ext/string/conversions.rb b/activesupport/lib/active_support/core_ext/string/conversions.rb
index 383d93e2cd..a0b771f41e 100644
--- a/activesupport/lib/active_support/core_ext/string/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/string/conversions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "date"
 require_relative "../time/calculations"
 
diff --git a/activesupport/lib/active_support/core_ext/string/exclude.rb b/activesupport/lib/active_support/core_ext/string/exclude.rb
index 0ac684f6ee..2893a6eeed 100644
--- a/activesupport/lib/active_support/core_ext/string/exclude.rb
+++ b/activesupport/lib/active_support/core_ext/string/exclude.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class String
   # The inverse of <tt>String#include?</tt>. Returns true if the string
   # does not include the other string.
diff --git a/activesupport/lib/active_support/core_ext/string/filters.rb b/activesupport/lib/active_support/core_ext/string/filters.rb
index a9ec2eb842..e05cf024f6 100644
--- a/activesupport/lib/active_support/core_ext/string/filters.rb
+++ b/activesupport/lib/active_support/core_ext/string/filters.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class String
   # Returns the string, first removing all whitespace on both ends of
   # the string, and then changing remaining consecutive whitespace
diff --git a/activesupport/lib/active_support/core_ext/string/indent.rb b/activesupport/lib/active_support/core_ext/string/indent.rb
index d7b58301d3..a38198a8e6 100644
--- a/activesupport/lib/active_support/core_ext/string/indent.rb
+++ b/activesupport/lib/active_support/core_ext/string/indent.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class String
   # Same as +indent+, except it indents the receiver in-place.
   #
diff --git a/activesupport/lib/active_support/core_ext/string/inflections.rb b/activesupport/lib/active_support/core_ext/string/inflections.rb
index 70c732ca44..78caa0832f 100644
--- a/activesupport/lib/active_support/core_ext/string/inflections.rb
+++ b/activesupport/lib/active_support/core_ext/string/inflections.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../inflector/methods"
 require_relative "../../inflector/transliterate"
 
diff --git a/activesupport/lib/active_support/core_ext/string/inquiry.rb b/activesupport/lib/active_support/core_ext/string/inquiry.rb
index dfa78b2ff8..0fe532fb8c 100644
--- a/activesupport/lib/active_support/core_ext/string/inquiry.rb
+++ b/activesupport/lib/active_support/core_ext/string/inquiry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../string_inquirer"
 
 class String
diff --git a/activesupport/lib/active_support/core_ext/string/multibyte.rb b/activesupport/lib/active_support/core_ext/string/multibyte.rb
index 56a1cede1a..403e4be011 100644
--- a/activesupport/lib/active_support/core_ext/string/multibyte.rb
+++ b/activesupport/lib/active_support/core_ext/string/multibyte.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../multibyte"
 
 class String
diff --git a/activesupport/lib/active_support/core_ext/string/output_safety.rb b/activesupport/lib/active_support/core_ext/string/output_safety.rb
index 607870237b..4bfc582eb5 100644
--- a/activesupport/lib/active_support/core_ext/string/output_safety.rb
+++ b/activesupport/lib/active_support/core_ext/string/output_safety.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "erb"
 require_relative "../kernel/singleton_class"
 require_relative "../../multibyte/unicode"
diff --git a/activesupport/lib/active_support/core_ext/string/starts_ends_with.rb b/activesupport/lib/active_support/core_ext/string/starts_ends_with.rb
index 641acf62d0..f072fbf7d7 100644
--- a/activesupport/lib/active_support/core_ext/string/starts_ends_with.rb
+++ b/activesupport/lib/active_support/core_ext/string/starts_ends_with.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class String
   alias_method :starts_with?, :start_with?
   alias_method :ends_with?, :end_with?
diff --git a/activesupport/lib/active_support/core_ext/string/strip.rb b/activesupport/lib/active_support/core_ext/string/strip.rb
index bb62e6c0ba..979b6bd767 100644
--- a/activesupport/lib/active_support/core_ext/string/strip.rb
+++ b/activesupport/lib/active_support/core_ext/string/strip.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class String
   # Strips indentation in heredocs.
   #
diff --git a/activesupport/lib/active_support/core_ext/string/zones.rb b/activesupport/lib/active_support/core_ext/string/zones.rb
index d8d22a6799..a911fdab3c 100644
--- a/activesupport/lib/active_support/core_ext/string/zones.rb
+++ b/activesupport/lib/active_support/core_ext/string/zones.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "conversions"
 require_relative "../time/zones"
 
diff --git a/activesupport/lib/active_support/core_ext/time.rb b/activesupport/lib/active_support/core_ext/time.rb
index 19d4d91dac..cfa9b82b06 100644
--- a/activesupport/lib/active_support/core_ext/time.rb
+++ b/activesupport/lib/active_support/core_ext/time.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "time/acts_like"
 require_relative "time/calculations"
 require_relative "time/compatibility"
diff --git a/activesupport/lib/active_support/core_ext/time/acts_like.rb b/activesupport/lib/active_support/core_ext/time/acts_like.rb
index 08756a2dae..776456506c 100644
--- a/activesupport/lib/active_support/core_ext/time/acts_like.rb
+++ b/activesupport/lib/active_support/core_ext/time/acts_like.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../object/acts_like"
 
 class Time
diff --git a/activesupport/lib/active_support/core_ext/time/calculations.rb b/activesupport/lib/active_support/core_ext/time/calculations.rb
index 9ba6bf8fa1..4cfb702674 100644
--- a/activesupport/lib/active_support/core_ext/time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/time/calculations.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../duration"
 require_relative "conversions"
 require_relative "../../time_with_zone"
diff --git a/activesupport/lib/active_support/core_ext/time/compatibility.rb b/activesupport/lib/active_support/core_ext/time/compatibility.rb
index a554e71b74..ce69e5f478 100644
--- a/activesupport/lib/active_support/core_ext/time/compatibility.rb
+++ b/activesupport/lib/active_support/core_ext/time/compatibility.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../date_and_time/compatibility"
 require_relative "../module/remove_method"
 
diff --git a/activesupport/lib/active_support/core_ext/time/conversions.rb b/activesupport/lib/active_support/core_ext/time/conversions.rb
index 0dbce99ccb..5cb0f9c980 100644
--- a/activesupport/lib/active_support/core_ext/time/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/time/conversions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../inflector/methods"
 require_relative "../../values/time_zone"
 
diff --git a/activesupport/lib/active_support/core_ext/time/zones.rb b/activesupport/lib/active_support/core_ext/time/zones.rb
index ba8b5b73f8..3794eab3f5 100644
--- a/activesupport/lib/active_support/core_ext/time/zones.rb
+++ b/activesupport/lib/active_support/core_ext/time/zones.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../../time_with_zone"
 require_relative "acts_like"
 require_relative "../date_and_time/zones"
diff --git a/activesupport/lib/active_support/core_ext/uri.rb b/activesupport/lib/active_support/core_ext/uri.rb
index 342a5fcd52..f93dbdf2cd 100644
--- a/activesupport/lib/active_support/core_ext/uri.rb
+++ b/activesupport/lib/active_support/core_ext/uri.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "uri"
 str = "\xE6\x97\xA5\xE6\x9C\xAC\xE8\xAA\x9E" # Ni-ho-nn-go in UTF-8, means Japanese.
 parser = URI::Parser.new
diff --git a/activesupport/lib/active_support/current_attributes.rb b/activesupport/lib/active_support/current_attributes.rb
index 872b0663c7..1857700486 100644
--- a/activesupport/lib/active_support/current_attributes.rb
+++ b/activesupport/lib/active_support/current_attributes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   # Abstract super class that provides a thread-isolated attributes singleton, which resets automatically
   # before and after each request. This allows you to keep all the per-request attributes easily
diff --git a/activesupport/lib/active_support/dependencies.rb b/activesupport/lib/active_support/dependencies.rb
index 05b9b5b211..a11d4a834b 100644
--- a/activesupport/lib/active_support/dependencies.rb
+++ b/activesupport/lib/active_support/dependencies.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "set"
 require "thread"
 require "concurrent/map"
diff --git a/activesupport/lib/active_support/dependencies/autoload.rb b/activesupport/lib/active_support/dependencies/autoload.rb
index 9e4d3b783b..fcf550be3d 100644
--- a/activesupport/lib/active_support/dependencies/autoload.rb
+++ b/activesupport/lib/active_support/dependencies/autoload.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../inflector/methods"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/dependencies/interlock.rb b/activesupport/lib/active_support/dependencies/interlock.rb
index b88cf08dd2..0d80484c00 100644
--- a/activesupport/lib/active_support/dependencies/interlock.rb
+++ b/activesupport/lib/active_support/dependencies/interlock.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../concurrency/share_lock"
 
 module ActiveSupport #:nodoc:
diff --git a/activesupport/lib/active_support/deprecation.rb b/activesupport/lib/active_support/deprecation.rb
index eaaf198ccb..3e914de316 100644
--- a/activesupport/lib/active_support/deprecation.rb
+++ b/activesupport/lib/active_support/deprecation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "singleton"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/deprecation/behaviors.rb b/activesupport/lib/active_support/deprecation/behaviors.rb
index 409f4cf6a6..5b7f67db53 100644
--- a/activesupport/lib/active_support/deprecation/behaviors.rb
+++ b/activesupport/lib/active_support/deprecation/behaviors.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../notifications"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/deprecation/constant_accessor.rb b/activesupport/lib/active_support/deprecation/constant_accessor.rb
index 895b23e8ef..17850a2b39 100644
--- a/activesupport/lib/active_support/deprecation/constant_accessor.rb
+++ b/activesupport/lib/active_support/deprecation/constant_accessor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../inflector/methods"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/deprecation/instance_delegator.rb b/activesupport/lib/active_support/deprecation/instance_delegator.rb
index 23eac0e5d3..4a62df4714 100644
--- a/activesupport/lib/active_support/deprecation/instance_delegator.rb
+++ b/activesupport/lib/active_support/deprecation/instance_delegator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../core_ext/kernel/singleton_class"
 require_relative "../core_ext/module/delegation"
 
diff --git a/activesupport/lib/active_support/deprecation/method_wrappers.rb b/activesupport/lib/active_support/deprecation/method_wrappers.rb
index ed41e9aaa4..94c7960a9d 100644
--- a/activesupport/lib/active_support/deprecation/method_wrappers.rb
+++ b/activesupport/lib/active_support/deprecation/method_wrappers.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../core_ext/module/aliasing"
 require_relative "../core_ext/array/extract_options"
 
diff --git a/activesupport/lib/active_support/deprecation/proxy_wrappers.rb b/activesupport/lib/active_support/deprecation/proxy_wrappers.rb
index 64aaef3e43..cd3d7dcad4 100644
--- a/activesupport/lib/active_support/deprecation/proxy_wrappers.rb
+++ b/activesupport/lib/active_support/deprecation/proxy_wrappers.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../inflector/methods"
 require_relative "../core_ext/regexp"
 
diff --git a/activesupport/lib/active_support/deprecation/reporting.rb b/activesupport/lib/active_support/deprecation/reporting.rb
index 140bdccbb3..f190e47b64 100644
--- a/activesupport/lib/active_support/deprecation/reporting.rb
+++ b/activesupport/lib/active_support/deprecation/reporting.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "rbconfig"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/descendants_tracker.rb b/activesupport/lib/active_support/descendants_tracker.rb
index 27861e01d0..4f759f2f26 100644
--- a/activesupport/lib/active_support/descendants_tracker.rb
+++ b/activesupport/lib/active_support/descendants_tracker.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   # This module provides an internal implementation to track descendants
   # which is faster than iterating through ObjectSpace.
diff --git a/activesupport/lib/active_support/duration.rb b/activesupport/lib/active_support/duration.rb
index 0ad591e683..15d550e3ee 100644
--- a/activesupport/lib/active_support/duration.rb
+++ b/activesupport/lib/active_support/duration.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "core_ext/array/conversions"
 require_relative "core_ext/module/delegation"
 require_relative "core_ext/object/acts_like"
diff --git a/activesupport/lib/active_support/duration/iso8601_parser.rb b/activesupport/lib/active_support/duration/iso8601_parser.rb
index 78a00b5e4f..10f9e1fd0f 100644
--- a/activesupport/lib/active_support/duration/iso8601_parser.rb
+++ b/activesupport/lib/active_support/duration/iso8601_parser.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "strscan"
 require_relative "../core_ext/regexp"
 
diff --git a/activesupport/lib/active_support/duration/iso8601_serializer.rb b/activesupport/lib/active_support/duration/iso8601_serializer.rb
index 83c3a46692..829f935e3a 100644
--- a/activesupport/lib/active_support/duration/iso8601_serializer.rb
+++ b/activesupport/lib/active_support/duration/iso8601_serializer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../core_ext/object/blank"
 require_relative "../core_ext/hash/transform_values"
 
diff --git a/activesupport/lib/active_support/evented_file_update_checker.rb b/activesupport/lib/active_support/evented_file_update_checker.rb
index f59f5d17dc..3c456beac6 100644
--- a/activesupport/lib/active_support/evented_file_update_checker.rb
+++ b/activesupport/lib/active_support/evented_file_update_checker.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "set"
 require "pathname"
 require "concurrent/atomic/atomic_boolean"
diff --git a/activesupport/lib/active_support/execution_wrapper.rb b/activesupport/lib/active_support/execution_wrapper.rb
index 3513e9023c..189c06b811 100644
--- a/activesupport/lib/active_support/execution_wrapper.rb
+++ b/activesupport/lib/active_support/execution_wrapper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "callbacks"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/executor.rb b/activesupport/lib/active_support/executor.rb
index 4a618d9fa2..2fd6325993 100644
--- a/activesupport/lib/active_support/executor.rb
+++ b/activesupport/lib/active_support/executor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "execution_wrapper"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/file_update_checker.rb b/activesupport/lib/active_support/file_update_checker.rb
index b9d8740569..0201e86d1e 100644
--- a/activesupport/lib/active_support/file_update_checker.rb
+++ b/activesupport/lib/active_support/file_update_checker.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "core_ext/time/calculations"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/gem_version.rb b/activesupport/lib/active_support/gem_version.rb
index 371a39a5e6..d6015b0161 100644
--- a/activesupport/lib/active_support/gem_version.rb
+++ b/activesupport/lib/active_support/gem_version.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   # Returns the version of the currently loaded Active Support as a <tt>Gem::Version</tt>.
   def self.gem_version
diff --git a/activesupport/lib/active_support/gzip.rb b/activesupport/lib/active_support/gzip.rb
index 95a86889ec..fd9263500c 100644
--- a/activesupport/lib/active_support/gzip.rb
+++ b/activesupport/lib/active_support/gzip.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "zlib"
 require "stringio"
 
diff --git a/activesupport/lib/active_support/hash_with_indifferent_access.rb b/activesupport/lib/active_support/hash_with_indifferent_access.rb
index 6c98960292..6ede4559ba 100644
--- a/activesupport/lib/active_support/hash_with_indifferent_access.rb
+++ b/activesupport/lib/active_support/hash_with_indifferent_access.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "core_ext/hash/keys"
 require_relative "core_ext/hash/reverse_merge"
 
diff --git a/activesupport/lib/active_support/i18n.rb b/activesupport/lib/active_support/i18n.rb
index 3f47da3b38..4548c89cbb 100644
--- a/activesupport/lib/active_support/i18n.rb
+++ b/activesupport/lib/active_support/i18n.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "core_ext/hash/deep_merge"
 require_relative "core_ext/hash/except"
 require_relative "core_ext/hash/slice"
diff --git a/activesupport/lib/active_support/i18n_railtie.rb b/activesupport/lib/active_support/i18n_railtie.rb
index 6809a650cf..6a249e3906 100644
--- a/activesupport/lib/active_support/i18n_railtie.rb
+++ b/activesupport/lib/active_support/i18n_railtie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "active_support"
 require_relative "file_update_checker"
 require_relative "core_ext/array/wrap"
diff --git a/activesupport/lib/active_support/inflections.rb b/activesupport/lib/active_support/inflections.rb
index 1b94ce9b1b..339931b865 100644
--- a/activesupport/lib/active_support/inflections.rb
+++ b/activesupport/lib/active_support/inflections.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "inflector/inflections"
 
 #--
diff --git a/activesupport/lib/active_support/inflector.rb b/activesupport/lib/active_support/inflector.rb
index a4bd8aaeb4..abfce1c17c 100644
--- a/activesupport/lib/active_support/inflector.rb
+++ b/activesupport/lib/active_support/inflector.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # in case active_support/inflector is required without the rest of active_support
 require_relative "inflector/inflections"
 require_relative "inflector/transliterate"
diff --git a/activesupport/lib/active_support/inflector/inflections.rb b/activesupport/lib/active_support/inflector/inflections.rb
index 2cb7828968..b8f7cc4c6d 100644
--- a/activesupport/lib/active_support/inflector/inflections.rb
+++ b/activesupport/lib/active_support/inflector/inflections.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "concurrent/map"
 require_relative "../core_ext/array/prepend_and_append"
 require_relative "../core_ext/regexp"
diff --git a/activesupport/lib/active_support/inflector/methods.rb b/activesupport/lib/active_support/inflector/methods.rb
index ba85d3bb33..0e6fd145a2 100644
--- a/activesupport/lib/active_support/inflector/methods.rb
+++ b/activesupport/lib/active_support/inflector/methods.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../inflections"
 require_relative "../core_ext/regexp"
 
diff --git a/activesupport/lib/active_support/inflector/transliterate.rb b/activesupport/lib/active_support/inflector/transliterate.rb
index 0775ee51bc..6267142628 100644
--- a/activesupport/lib/active_support/inflector/transliterate.rb
+++ b/activesupport/lib/active_support/inflector/transliterate.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../core_ext/string/multibyte"
 require_relative "../i18n"
 
diff --git a/activesupport/lib/active_support/json.rb b/activesupport/lib/active_support/json.rb
index e0a6ab3768..043750e05c 100644
--- a/activesupport/lib/active_support/json.rb
+++ b/activesupport/lib/active_support/json.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 require_relative "json/decoding"
 require_relative "json/encoding"
diff --git a/activesupport/lib/active_support/json/decoding.rb b/activesupport/lib/active_support/json/decoding.rb
index c60ebb2795..515a11edf1 100644
--- a/activesupport/lib/active_support/json/decoding.rb
+++ b/activesupport/lib/active_support/json/decoding.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../core_ext/module/attribute_accessors"
 require_relative "../core_ext/module/delegation"
 require "json"
diff --git a/activesupport/lib/active_support/json/encoding.rb b/activesupport/lib/active_support/json/encoding.rb
index e7679e4630..153f1fdbd2 100644
--- a/activesupport/lib/active_support/json/encoding.rb
+++ b/activesupport/lib/active_support/json/encoding.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../core_ext/object/json"
 require_relative "../core_ext/module/delegation"
 
diff --git a/activesupport/lib/active_support/key_generator.rb b/activesupport/lib/active_support/key_generator.rb
index 23ab804eb1..a0b2a70ee3 100644
--- a/activesupport/lib/active_support/key_generator.rb
+++ b/activesupport/lib/active_support/key_generator.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "concurrent/map"
 require "openssl"
 
diff --git a/activesupport/lib/active_support/lazy_load_hooks.rb b/activesupport/lib/active_support/lazy_load_hooks.rb
index 720ed47331..b1fc6b331b 100644
--- a/activesupport/lib/active_support/lazy_load_hooks.rb
+++ b/activesupport/lib/active_support/lazy_load_hooks.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   # lazy_load_hooks allows Rails to lazily load a lot of components and thus
   # making the app boot faster. Because of this feature now there is no need to
diff --git a/activesupport/lib/active_support/log_subscriber.rb b/activesupport/lib/active_support/log_subscriber.rb
index 2b494e6d6c..a5b502a30e 100644
--- a/activesupport/lib/active_support/log_subscriber.rb
+++ b/activesupport/lib/active_support/log_subscriber.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "core_ext/module/attribute_accessors"
 require_relative "core_ext/class/attribute"
 require_relative "subscriber"
diff --git a/activesupport/lib/active_support/log_subscriber/test_helper.rb b/activesupport/lib/active_support/log_subscriber/test_helper.rb
index 469e6c6bb4..7f25d6b0b3 100644
--- a/activesupport/lib/active_support/log_subscriber/test_helper.rb
+++ b/activesupport/lib/active_support/log_subscriber/test_helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../log_subscriber"
 require_relative "../logger"
 require_relative "../notifications"
diff --git a/activesupport/lib/active_support/logger.rb b/activesupport/lib/active_support/logger.rb
index 677ec8d5bc..2bbff5892d 100644
--- a/activesupport/lib/active_support/logger.rb
+++ b/activesupport/lib/active_support/logger.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "logger_silence"
 require_relative "logger_thread_safe_level"
 require "logger"
diff --git a/activesupport/lib/active_support/logger_silence.rb b/activesupport/lib/active_support/logger_silence.rb
index 7f85f54542..5c8d4dba5e 100644
--- a/activesupport/lib/active_support/logger_silence.rb
+++ b/activesupport/lib/active_support/logger_silence.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "concern"
 require_relative "core_ext/module/attribute_accessors"
 require "concurrent"
diff --git a/activesupport/lib/active_support/logger_thread_safe_level.rb b/activesupport/lib/active_support/logger_thread_safe_level.rb
index 405bb239cf..4b5f2e7fb3 100644
--- a/activesupport/lib/active_support/logger_thread_safe_level.rb
+++ b/activesupport/lib/active_support/logger_thread_safe_level.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "concern"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/message_encryptor.rb b/activesupport/lib/active_support/message_encryptor.rb
index 3aaa1ae02c..689a2202f7 100644
--- a/activesupport/lib/active_support/message_encryptor.rb
+++ b/activesupport/lib/active_support/message_encryptor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "openssl"
 require "base64"
 require_relative "core_ext/array/extract_options"
diff --git a/activesupport/lib/active_support/message_verifier.rb b/activesupport/lib/active_support/message_verifier.rb
index e71dcd3a5b..2eb09e41e0 100644
--- a/activesupport/lib/active_support/message_verifier.rb
+++ b/activesupport/lib/active_support/message_verifier.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "base64"
 require_relative "core_ext/object/blank"
 require_relative "security_utils"
diff --git a/activesupport/lib/active_support/multibyte.rb b/activesupport/lib/active_support/multibyte.rb
index f7c7befee0..0a3418ae95 100644
--- a/activesupport/lib/active_support/multibyte.rb
+++ b/activesupport/lib/active_support/multibyte.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport #:nodoc:
   module Multibyte
     autoload :Chars, "active_support/multibyte/chars"
diff --git a/activesupport/lib/active_support/multibyte/chars.rb b/activesupport/lib/active_support/multibyte/chars.rb
index e4c544d1fa..7bd1200fa6 100644
--- a/activesupport/lib/active_support/multibyte/chars.rb
+++ b/activesupport/lib/active_support/multibyte/chars.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../json"
 require_relative "../core_ext/string/access"
 require_relative "../core_ext/string/behavior"
diff --git a/activesupport/lib/active_support/multibyte/unicode.rb b/activesupport/lib/active_support/multibyte/unicode.rb
index 8223e45e5a..92575b1c9b 100644
--- a/activesupport/lib/active_support/multibyte/unicode.rb
+++ b/activesupport/lib/active_support/multibyte/unicode.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module Multibyte
     module Unicode
diff --git a/activesupport/lib/active_support/notifications.rb b/activesupport/lib/active_support/notifications.rb
index 10e40e04f9..88ba85d8c7 100644
--- a/activesupport/lib/active_support/notifications.rb
+++ b/activesupport/lib/active_support/notifications.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "notifications/instrumenter"
 require_relative "notifications/fanout"
 require_relative "per_thread_registry"
diff --git a/activesupport/lib/active_support/notifications/fanout.rb b/activesupport/lib/active_support/notifications/fanout.rb
index 9da115f552..b69d1bcd25 100644
--- a/activesupport/lib/active_support/notifications/fanout.rb
+++ b/activesupport/lib/active_support/notifications/fanout.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "mutex_m"
 require "concurrent/map"
 
diff --git a/activesupport/lib/active_support/notifications/instrumenter.rb b/activesupport/lib/active_support/notifications/instrumenter.rb
index e11e2e0689..00936f5b9e 100644
--- a/activesupport/lib/active_support/notifications/instrumenter.rb
+++ b/activesupport/lib/active_support/notifications/instrumenter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "securerandom"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/number_helper.rb b/activesupport/lib/active_support/number_helper.rb
index 9cb2821cb6..965664eb65 100644
--- a/activesupport/lib/active_support/number_helper.rb
+++ b/activesupport/lib/active_support/number_helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module NumberHelper
     extend ActiveSupport::Autoload
diff --git a/activesupport/lib/active_support/number_helper/number_converter.rb b/activesupport/lib/active_support/number_helper/number_converter.rb
index f3fed6e88b..d2be18ce27 100644
--- a/activesupport/lib/active_support/number_helper/number_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_converter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../core_ext/big_decimal/conversions"
 require_relative "../core_ext/object/blank"
 require_relative "../core_ext/hash/keys"
diff --git a/activesupport/lib/active_support/number_helper/number_to_currency_converter.rb b/activesupport/lib/active_support/number_helper/number_to_currency_converter.rb
index 7bd2d4869a..c260b5b126 100644
--- a/activesupport/lib/active_support/number_helper/number_to_currency_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_currency_converter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../core_ext/numeric/inquiry"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/number_helper/number_to_delimited_converter.rb b/activesupport/lib/active_support/number_helper/number_to_delimited_converter.rb
index e3b35531b1..620e6b4282 100644
--- a/activesupport/lib/active_support/number_helper/number_to_delimited_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_delimited_converter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module NumberHelper
     class NumberToDelimitedConverter < NumberConverter #:nodoc:
diff --git a/activesupport/lib/active_support/number_helper/number_to_human_converter.rb b/activesupport/lib/active_support/number_helper/number_to_human_converter.rb
index 040343b5dd..852a76fbb6 100644
--- a/activesupport/lib/active_support/number_helper/number_to_human_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_human_converter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module NumberHelper
     class NumberToHumanConverter < NumberConverter # :nodoc:
diff --git a/activesupport/lib/active_support/number_helper/number_to_human_size_converter.rb b/activesupport/lib/active_support/number_helper/number_to_human_size_converter.rb
index f263dbe9f8..a1ebb92fe7 100644
--- a/activesupport/lib/active_support/number_helper/number_to_human_size_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_human_size_converter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module NumberHelper
     class NumberToHumanSizeConverter < NumberConverter #:nodoc:
diff --git a/activesupport/lib/active_support/number_helper/number_to_percentage_converter.rb b/activesupport/lib/active_support/number_helper/number_to_percentage_converter.rb
index ac647ca9b7..9285d7d93f 100644
--- a/activesupport/lib/active_support/number_helper/number_to_percentage_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_percentage_converter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module NumberHelper
     class NumberToPercentageConverter < NumberConverter # :nodoc:
diff --git a/activesupport/lib/active_support/number_helper/number_to_phone_converter.rb b/activesupport/lib/active_support/number_helper/number_to_phone_converter.rb
index 3546ee5c2a..e1f2fec55b 100644
--- a/activesupport/lib/active_support/number_helper/number_to_phone_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_phone_converter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module NumberHelper
     class NumberToPhoneConverter < NumberConverter #:nodoc:
diff --git a/activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb b/activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb
index c32d85a45f..6e8b5ee653 100644
--- a/activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb
+++ b/activesupport/lib/active_support/number_helper/number_to_rounded_converter.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module NumberHelper
     class NumberToRoundedConverter < NumberConverter # :nodoc:
diff --git a/activesupport/lib/active_support/number_helper/rounding_helper.rb b/activesupport/lib/active_support/number_helper/rounding_helper.rb
index 63b48444a6..f5d5f4664b 100644
--- a/activesupport/lib/active_support/number_helper/rounding_helper.rb
+++ b/activesupport/lib/active_support/number_helper/rounding_helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module NumberHelper
     class RoundingHelper # :nodoc:
diff --git a/activesupport/lib/active_support/option_merger.rb b/activesupport/lib/active_support/option_merger.rb
index 9edb0e6cd8..5788332349 100644
--- a/activesupport/lib/active_support/option_merger.rb
+++ b/activesupport/lib/active_support/option_merger.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "core_ext/hash/deep_merge"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/ordered_hash.rb b/activesupport/lib/active_support/ordered_hash.rb
index 3aa0a14f04..b07b89447e 100644
--- a/activesupport/lib/active_support/ordered_hash.rb
+++ b/activesupport/lib/active_support/ordered_hash.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "yaml"
 
 YAML.add_builtin_type("omap") do |type, val|
diff --git a/activesupport/lib/active_support/ordered_options.rb b/activesupport/lib/active_support/ordered_options.rb
index c0f39a392b..457418a79a 100644
--- a/activesupport/lib/active_support/ordered_options.rb
+++ b/activesupport/lib/active_support/ordered_options.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "core_ext/object/blank"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/per_thread_registry.rb b/activesupport/lib/active_support/per_thread_registry.rb
index 1e0d8345a0..662c88d17d 100644
--- a/activesupport/lib/active_support/per_thread_registry.rb
+++ b/activesupport/lib/active_support/per_thread_registry.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "core_ext/module/delegation"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/proxy_object.rb b/activesupport/lib/active_support/proxy_object.rb
index 20a0fd8e62..df84ab6225 100644
--- a/activesupport/lib/active_support/proxy_object.rb
+++ b/activesupport/lib/active_support/proxy_object.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   # A class with no predefined methods that behaves similarly to Builder's
   # BlankSlate. Used for proxy classes.
diff --git a/activesupport/lib/active_support/rails.rb b/activesupport/lib/active_support/rails.rb
index 656af6dee9..c4fae94d5e 100644
--- a/activesupport/lib/active_support/rails.rb
+++ b/activesupport/lib/active_support/rails.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # This is private interface.
 #
 # Rails components cherry pick from Active Support as needed, but there are a
diff --git a/activesupport/lib/active_support/railtie.rb b/activesupport/lib/active_support/railtie.rb
index 3377748263..7903d229c0 100644
--- a/activesupport/lib/active_support/railtie.rb
+++ b/activesupport/lib/active_support/railtie.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "active_support"
 require_relative "i18n_railtie"
 
diff --git a/activesupport/lib/active_support/reloader.rb b/activesupport/lib/active_support/reloader.rb
index a87c82e68a..6e81c95961 100644
--- a/activesupport/lib/active_support/reloader.rb
+++ b/activesupport/lib/active_support/reloader.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "execution_wrapper"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/rescuable.rb b/activesupport/lib/active_support/rescuable.rb
index 06f6a71de4..db736f5c23 100644
--- a/activesupport/lib/active_support/rescuable.rb
+++ b/activesupport/lib/active_support/rescuable.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "concern"
 require_relative "core_ext/class/attribute"
 require_relative "core_ext/string/inflections"
diff --git a/activesupport/lib/active_support/security_utils.rb b/activesupport/lib/active_support/security_utils.rb
index b655d64449..2e61a72213 100644
--- a/activesupport/lib/active_support/security_utils.rb
+++ b/activesupport/lib/active_support/security_utils.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "digest"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/string_inquirer.rb b/activesupport/lib/active_support/string_inquirer.rb
index 90eac89c9e..03bcbb2555 100644
--- a/activesupport/lib/active_support/string_inquirer.rb
+++ b/activesupport/lib/active_support/string_inquirer.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   # Wrapping a string in this class gives you a prettier way to test
   # for equality. The value returned by <tt>Rails.env</tt> is wrapped
diff --git a/activesupport/lib/active_support/subscriber.rb b/activesupport/lib/active_support/subscriber.rb
index 3a54482c75..23268e990a 100644
--- a/activesupport/lib/active_support/subscriber.rb
+++ b/activesupport/lib/active_support/subscriber.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "per_thread_registry"
 require_relative "notifications"
 
diff --git a/activesupport/lib/active_support/tagged_logging.rb b/activesupport/lib/active_support/tagged_logging.rb
index 90d096c397..7c06c0579f 100644
--- a/activesupport/lib/active_support/tagged_logging.rb
+++ b/activesupport/lib/active_support/tagged_logging.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "core_ext/module/delegation"
 require_relative "core_ext/object/blank"
 require "logger"
diff --git a/activesupport/lib/active_support/test_case.rb b/activesupport/lib/active_support/test_case.rb
index f2940a176f..df2d3002c9 100644
--- a/activesupport/lib/active_support/test_case.rb
+++ b/activesupport/lib/active_support/test_case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 gem "minitest" # make sure we get the gem, not stdlib
 require "minitest"
 require_relative "testing/tagged_logging"
diff --git a/activesupport/lib/active_support/testing/assertions.rb b/activesupport/lib/active_support/testing/assertions.rb
index 28e1df8870..d7bb5e5bdf 100644
--- a/activesupport/lib/active_support/testing/assertions.rb
+++ b/activesupport/lib/active_support/testing/assertions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module Testing
     module Assertions
diff --git a/activesupport/lib/active_support/testing/autorun.rb b/activesupport/lib/active_support/testing/autorun.rb
index a18788f38e..40ae696a34 100644
--- a/activesupport/lib/active_support/testing/autorun.rb
+++ b/activesupport/lib/active_support/testing/autorun.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 gem "minitest"
 
 require "minitest"
diff --git a/activesupport/lib/active_support/testing/constant_lookup.rb b/activesupport/lib/active_support/testing/constant_lookup.rb
index c0b58aba96..a231697979 100644
--- a/activesupport/lib/active_support/testing/constant_lookup.rb
+++ b/activesupport/lib/active_support/testing/constant_lookup.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../concern"
 require_relative "../inflector"
 
diff --git a/activesupport/lib/active_support/testing/declarative.rb b/activesupport/lib/active_support/testing/declarative.rb
index 53ab3ebf78..601f6fb16d 100644
--- a/activesupport/lib/active_support/testing/declarative.rb
+++ b/activesupport/lib/active_support/testing/declarative.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module Testing
     module Declarative
diff --git a/activesupport/lib/active_support/testing/deprecation.rb b/activesupport/lib/active_support/testing/deprecation.rb
index 6ee49530f0..1145afceff 100644
--- a/activesupport/lib/active_support/testing/deprecation.rb
+++ b/activesupport/lib/active_support/testing/deprecation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../deprecation"
 require_relative "../core_ext/regexp"
 
diff --git a/activesupport/lib/active_support/testing/file_fixtures.rb b/activesupport/lib/active_support/testing/file_fixtures.rb
index affb84cda5..56f80fb547 100644
--- a/activesupport/lib/active_support/testing/file_fixtures.rb
+++ b/activesupport/lib/active_support/testing/file_fixtures.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module Testing
     # Adds simple access to sample files called file fixtures.
diff --git a/activesupport/lib/active_support/testing/isolation.rb b/activesupport/lib/active_support/testing/isolation.rb
index 54c3263efa..4d43c06085 100644
--- a/activesupport/lib/active_support/testing/isolation.rb
+++ b/activesupport/lib/active_support/testing/isolation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module Testing
     module Isolation
diff --git a/activesupport/lib/active_support/testing/method_call_assertions.rb b/activesupport/lib/active_support/testing/method_call_assertions.rb
index 6b07416fdc..d33224e9c3 100644
--- a/activesupport/lib/active_support/testing/method_call_assertions.rb
+++ b/activesupport/lib/active_support/testing/method_call_assertions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "minitest/mock"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/testing/setup_and_teardown.rb b/activesupport/lib/active_support/testing/setup_and_teardown.rb
index c39f3bac2b..e80b8d17ef 100644
--- a/activesupport/lib/active_support/testing/setup_and_teardown.rb
+++ b/activesupport/lib/active_support/testing/setup_and_teardown.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../concern"
 require_relative "../callbacks"
 
diff --git a/activesupport/lib/active_support/testing/stream.rb b/activesupport/lib/active_support/testing/stream.rb
index 1d06b94559..4e8303f058 100644
--- a/activesupport/lib/active_support/testing/stream.rb
+++ b/activesupport/lib/active_support/testing/stream.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module Testing
     module Stream #:nodoc:
diff --git a/activesupport/lib/active_support/testing/tagged_logging.rb b/activesupport/lib/active_support/testing/tagged_logging.rb
index afdff87b45..3ca45b4ab5 100644
--- a/activesupport/lib/active_support/testing/tagged_logging.rb
+++ b/activesupport/lib/active_support/testing/tagged_logging.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   module Testing
     # Logs a "PostsControllerTest: test name" heading before each test to
diff --git a/activesupport/lib/active_support/testing/time_helpers.rb b/activesupport/lib/active_support/testing/time_helpers.rb
index 4db7065ddf..eaccbb97eb 100644
--- a/activesupport/lib/active_support/testing/time_helpers.rb
+++ b/activesupport/lib/active_support/testing/time_helpers.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../core_ext/string/strip" # for strip_heredoc
 require_relative "../core_ext/time/calculations"
 require "concurrent/map"
diff --git a/activesupport/lib/active_support/time.rb b/activesupport/lib/active_support/time.rb
index bc5f0177e2..6004119717 100644
--- a/activesupport/lib/active_support/time.rb
+++ b/activesupport/lib/active_support/time.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveSupport
   autoload :Duration, "active_support/duration"
   autoload :TimeWithZone, "active_support/time_with_zone"
diff --git a/activesupport/lib/active_support/time_with_zone.rb b/activesupport/lib/active_support/time_with_zone.rb
index 67d4a8683b..444a714d53 100644
--- a/activesupport/lib/active_support/time_with_zone.rb
+++ b/activesupport/lib/active_support/time_with_zone.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "duration"
 require_relative "values/time_zone"
 require_relative "core_ext/object/acts_like"
diff --git a/activesupport/lib/active_support/values/time_zone.rb b/activesupport/lib/active_support/values/time_zone.rb
index 0659b39981..35c9509060 100644
--- a/activesupport/lib/active_support/values/time_zone.rb
+++ b/activesupport/lib/active_support/values/time_zone.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "tzinfo"
 require "concurrent/map"
 require_relative "../core_ext/object/blank"
diff --git a/activesupport/lib/active_support/version.rb b/activesupport/lib/active_support/version.rb
index 20b91ac911..e2afb871e7 100644
--- a/activesupport/lib/active_support/version.rb
+++ b/activesupport/lib/active_support/version.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "gem_version"
 
 module ActiveSupport
diff --git a/activesupport/lib/active_support/xml_mini.rb b/activesupport/lib/active_support/xml_mini.rb
index 14725ffd64..7163dee68a 100644
--- a/activesupport/lib/active_support/xml_mini.rb
+++ b/activesupport/lib/active_support/xml_mini.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "time"
 require "base64"
 require "bigdecimal"
diff --git a/activesupport/lib/active_support/xml_mini/jdom.rb b/activesupport/lib/active_support/xml_mini/jdom.rb
index 331d9960e7..8529c5f73b 100644
--- a/activesupport/lib/active_support/xml_mini/jdom.rb
+++ b/activesupport/lib/active_support/xml_mini/jdom.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 raise "JRuby is required to use the JDOM backend for XmlMini" unless RUBY_PLATFORM.include?("java")
 
 require "jruby"
diff --git a/activesupport/lib/active_support/xml_mini/libxml.rb b/activesupport/lib/active_support/xml_mini/libxml.rb
index d7097dcc64..2524d6aee2 100644
--- a/activesupport/lib/active_support/xml_mini/libxml.rb
+++ b/activesupport/lib/active_support/xml_mini/libxml.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "libxml"
 require_relative "../core_ext/object/blank"
 require "stringio"
diff --git a/activesupport/lib/active_support/xml_mini/libxmlsax.rb b/activesupport/lib/active_support/xml_mini/libxmlsax.rb
index 0cfa2b2cd3..8ea4e9b292 100644
--- a/activesupport/lib/active_support/xml_mini/libxmlsax.rb
+++ b/activesupport/lib/active_support/xml_mini/libxmlsax.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "libxml"
 require_relative "../core_ext/object/blank"
 require "stringio"
diff --git a/activesupport/lib/active_support/xml_mini/nokogiri.rb b/activesupport/lib/active_support/xml_mini/nokogiri.rb
index 57d8cec0c6..087112830e 100644
--- a/activesupport/lib/active_support/xml_mini/nokogiri.rb
+++ b/activesupport/lib/active_support/xml_mini/nokogiri.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 begin
   require "nokogiri"
 rescue LoadError => e
diff --git a/activesupport/lib/active_support/xml_mini/nokogirisax.rb b/activesupport/lib/active_support/xml_mini/nokogirisax.rb
index 8fc1dfa727..7a9cd88af7 100644
--- a/activesupport/lib/active_support/xml_mini/nokogirisax.rb
+++ b/activesupport/lib/active_support/xml_mini/nokogirisax.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 begin
   require "nokogiri"
 rescue LoadError => e
diff --git a/activesupport/lib/active_support/xml_mini/rexml.rb b/activesupport/lib/active_support/xml_mini/rexml.rb
index 04d12c6109..a5fea919a7 100644
--- a/activesupport/lib/active_support/xml_mini/rexml.rb
+++ b/activesupport/lib/active_support/xml_mini/rexml.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "../core_ext/kernel/reporting"
 require_relative "../core_ext/object/blank"
 require "stringio"
diff --git a/activesupport/test/abstract_unit.rb b/activesupport/test/abstract_unit.rb
index c4f34c0abf..3004272629 100644
--- a/activesupport/test/abstract_unit.rb
+++ b/activesupport/test/abstract_unit.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 ORIG_ARGV = ARGV.dup
 
 require "active_support/core_ext/kernel/reporting"
diff --git a/activesupport/test/array_inquirer_test.rb b/activesupport/test/array_inquirer_test.rb
index 5b2bc82905..c674a80d29 100644
--- a/activesupport/test/array_inquirer_test.rb
+++ b/activesupport/test/array_inquirer_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/array"
 
diff --git a/activesupport/test/autoload_test.rb b/activesupport/test/autoload_test.rb
index 6c8aa3e055..65838041ea 100644
--- a/activesupport/test/autoload_test.rb
+++ b/activesupport/test/autoload_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class TestAutoloadModule < ActiveSupport::TestCase
diff --git a/activesupport/test/autoloading_fixtures/a/b.rb b/activesupport/test/autoloading_fixtures/a/b.rb
index 0dbbbbd181..8f2d83719d 100644
--- a/activesupport/test/autoloading_fixtures/a/b.rb
+++ b/activesupport/test/autoloading_fixtures/a/b.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class A::B
 end
diff --git a/activesupport/test/autoloading_fixtures/a/c/d.rb b/activesupport/test/autoloading_fixtures/a/c/d.rb
index 2c0ec5f182..fd50bb95c6 100644
--- a/activesupport/test/autoloading_fixtures/a/c/d.rb
+++ b/activesupport/test/autoloading_fixtures/a/c/d.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class A::C::D
 end
diff --git a/activesupport/test/autoloading_fixtures/a/c/em/f.rb b/activesupport/test/autoloading_fixtures/a/c/em/f.rb
index 3ff1b7efa0..298b63c916 100644
--- a/activesupport/test/autoloading_fixtures/a/c/em/f.rb
+++ b/activesupport/test/autoloading_fixtures/a/c/em/f.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class A::C::EM::F
 end
diff --git a/activesupport/test/autoloading_fixtures/application.rb b/activesupport/test/autoloading_fixtures/application.rb
index d7d3096dcb..ae3ccf487e 100644
--- a/activesupport/test/autoloading_fixtures/application.rb
+++ b/activesupport/test/autoloading_fixtures/application.rb
@@ -1 +1,2 @@
+# frozen_string_literal: true
 ApplicationController = 10
diff --git a/activesupport/test/autoloading_fixtures/circular1.rb b/activesupport/test/autoloading_fixtures/circular1.rb
index a45761f066..f6041bde77 100644
--- a/activesupport/test/autoloading_fixtures/circular1.rb
+++ b/activesupport/test/autoloading_fixtures/circular1.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 silence_warnings do
   Circular2
 end
diff --git a/activesupport/test/autoloading_fixtures/circular2.rb b/activesupport/test/autoloading_fixtures/circular2.rb
index c847fa5001..178bbca3bd 100644
--- a/activesupport/test/autoloading_fixtures/circular2.rb
+++ b/activesupport/test/autoloading_fixtures/circular2.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 Circular1
 
 class Circular2
diff --git a/activesupport/test/autoloading_fixtures/class_folder.rb b/activesupport/test/autoloading_fixtures/class_folder.rb
index 6ee8182214..48c2993600 100644
--- a/activesupport/test/autoloading_fixtures/class_folder.rb
+++ b/activesupport/test/autoloading_fixtures/class_folder.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class ClassFolder
   ConstantInClassFolder = "indeed"
 end
diff --git a/activesupport/test/autoloading_fixtures/class_folder/class_folder_subclass.rb b/activesupport/test/autoloading_fixtures/class_folder/class_folder_subclass.rb
index 4df069cab6..866d3547f6 100644
--- a/activesupport/test/autoloading_fixtures/class_folder/class_folder_subclass.rb
+++ b/activesupport/test/autoloading_fixtures/class_folder/class_folder_subclass.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class ClassFolder::ClassFolderSubclass < ClassFolder
   ConstantInClassFolder = "indeed"
 end
diff --git a/activesupport/test/autoloading_fixtures/class_folder/inline_class.rb b/activesupport/test/autoloading_fixtures/class_folder/inline_class.rb
index 8235e90724..6c20a3a9a7 100644
--- a/activesupport/test/autoloading_fixtures/class_folder/inline_class.rb
+++ b/activesupport/test/autoloading_fixtures/class_folder/inline_class.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class ClassFolder::InlineClass
 end
diff --git a/activesupport/test/autoloading_fixtures/class_folder/nested_class.rb b/activesupport/test/autoloading_fixtures/class_folder/nested_class.rb
index 57a13d89ea..ee35eac3fc 100644
--- a/activesupport/test/autoloading_fixtures/class_folder/nested_class.rb
+++ b/activesupport/test/autoloading_fixtures/class_folder/nested_class.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class ClassFolder
   class NestedClass
   end
diff --git a/activesupport/test/autoloading_fixtures/conflict.rb b/activesupport/test/autoloading_fixtures/conflict.rb
index d7f42b5d5f..6731ea51d8 100644
--- a/activesupport/test/autoloading_fixtures/conflict.rb
+++ b/activesupport/test/autoloading_fixtures/conflict.rb
@@ -1 +1,2 @@
+# frozen_string_literal: true
 Conflict = 2
diff --git a/activesupport/test/autoloading_fixtures/counting_loader.rb b/activesupport/test/autoloading_fixtures/counting_loader.rb
index 4225c4412c..2a4001b815 100644
--- a/activesupport/test/autoloading_fixtures/counting_loader.rb
+++ b/activesupport/test/autoloading_fixtures/counting_loader.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 $counting_loaded_times ||= 0
 $counting_loaded_times += 1
 
diff --git a/activesupport/test/autoloading_fixtures/cross_site_dependency.rb b/activesupport/test/autoloading_fixtures/cross_site_dependency.rb
index de941bf271..4eff14e888 100644
--- a/activesupport/test/autoloading_fixtures/cross_site_dependency.rb
+++ b/activesupport/test/autoloading_fixtures/cross_site_dependency.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class CrossSiteDependency
 end
diff --git a/activesupport/test/autoloading_fixtures/d.rb b/activesupport/test/autoloading_fixtures/d.rb
index 52850e1e1a..c4217362d8 100644
--- a/activesupport/test/autoloading_fixtures/d.rb
+++ b/activesupport/test/autoloading_fixtures/d.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class D
 end
diff --git a/activesupport/test/autoloading_fixtures/em.rb b/activesupport/test/autoloading_fixtures/em.rb
index e47024999e..38bb323e9e 100644
--- a/activesupport/test/autoloading_fixtures/em.rb
+++ b/activesupport/test/autoloading_fixtures/em.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class EM
 end
diff --git a/activesupport/test/autoloading_fixtures/html/some_class.rb b/activesupport/test/autoloading_fixtures/html/some_class.rb
index b43d15d891..495372fef3 100644
--- a/activesupport/test/autoloading_fixtures/html/some_class.rb
+++ b/activesupport/test/autoloading_fixtures/html/some_class.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module HTML
   class SomeClass
   end
diff --git a/activesupport/test/autoloading_fixtures/load_path/loaded_constant.rb b/activesupport/test/autoloading_fixtures/load_path/loaded_constant.rb
index d2c4f6b0c5..e5f73d9f0c 100644
--- a/activesupport/test/autoloading_fixtures/load_path/loaded_constant.rb
+++ b/activesupport/test/autoloading_fixtures/load_path/loaded_constant.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 module LoadedConstant
 end
diff --git a/activesupport/test/autoloading_fixtures/loads_constant.rb b/activesupport/test/autoloading_fixtures/loads_constant.rb
index 0b30dc8bca..cb7b381de3 100644
--- a/activesupport/test/autoloading_fixtures/loads_constant.rb
+++ b/activesupport/test/autoloading_fixtures/loads_constant.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module LoadsConstant
 end
 
diff --git a/activesupport/test/autoloading_fixtures/module_folder/inline_class.rb b/activesupport/test/autoloading_fixtures/module_folder/inline_class.rb
index ca83437046..5ed98cd4cf 100644
--- a/activesupport/test/autoloading_fixtures/module_folder/inline_class.rb
+++ b/activesupport/test/autoloading_fixtures/module_folder/inline_class.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class ModuleFolder::InlineClass
 end
diff --git a/activesupport/test/autoloading_fixtures/module_folder/nested_class.rb b/activesupport/test/autoloading_fixtures/module_folder/nested_class.rb
index fc4076bd0a..afed4b0a7e 100644
--- a/activesupport/test/autoloading_fixtures/module_folder/nested_class.rb
+++ b/activesupport/test/autoloading_fixtures/module_folder/nested_class.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ModuleFolder
   class NestedClass
   end
diff --git a/activesupport/test/autoloading_fixtures/module_folder/nested_sibling.rb b/activesupport/test/autoloading_fixtures/module_folder/nested_sibling.rb
index 04c426833e..a16cc566dd 100644
--- a/activesupport/test/autoloading_fixtures/module_folder/nested_sibling.rb
+++ b/activesupport/test/autoloading_fixtures/module_folder/nested_sibling.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class ModuleFolder::NestedSibling
 end
diff --git a/activesupport/test/autoloading_fixtures/module_with_custom_const_missing/a/b.rb b/activesupport/test/autoloading_fixtures/module_with_custom_const_missing/a/b.rb
index 4f2020c503..a6ed49e0be 100644
--- a/activesupport/test/autoloading_fixtures/module_with_custom_const_missing/a/b.rb
+++ b/activesupport/test/autoloading_fixtures/module_with_custom_const_missing/a/b.rb
@@ -1 +1,2 @@
+# frozen_string_literal: true
 ModuleWithCustomConstMissing::A::B = "10"
diff --git a/activesupport/test/autoloading_fixtures/multiple_constant_file.rb b/activesupport/test/autoloading_fixtures/multiple_constant_file.rb
index a9ff4eb89c..33d371c830 100644
--- a/activesupport/test/autoloading_fixtures/multiple_constant_file.rb
+++ b/activesupport/test/autoloading_fixtures/multiple_constant_file.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 MultipleConstantFile = 10
 SiblingConstant = MultipleConstantFile * 2
diff --git a/activesupport/test/autoloading_fixtures/prepend.rb b/activesupport/test/autoloading_fixtures/prepend.rb
index 3134d1df2b..1bef4ab5b3 100644
--- a/activesupport/test/autoloading_fixtures/prepend.rb
+++ b/activesupport/test/autoloading_fixtures/prepend.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class SubClassConflict
 end
 
diff --git a/activesupport/test/autoloading_fixtures/prepend/sub_class_conflict.rb b/activesupport/test/autoloading_fixtures/prepend/sub_class_conflict.rb
index 090dda3043..d76b575b06 100644
--- a/activesupport/test/autoloading_fixtures/prepend/sub_class_conflict.rb
+++ b/activesupport/test/autoloading_fixtures/prepend/sub_class_conflict.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class Prepend::SubClassConflict
 end
diff --git a/activesupport/test/autoloading_fixtures/raises_arbitrary_exception.rb b/activesupport/test/autoloading_fixtures/raises_arbitrary_exception.rb
index e477ab21d0..814c41c004 100644
--- a/activesupport/test/autoloading_fixtures/raises_arbitrary_exception.rb
+++ b/activesupport/test/autoloading_fixtures/raises_arbitrary_exception.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 RaisesArbitraryException = 1
 _ = A::B # Autoloading recursion, also expected to be watched and discarded.
 
diff --git a/activesupport/test/autoloading_fixtures/raises_name_error.rb b/activesupport/test/autoloading_fixtures/raises_name_error.rb
index a49960abf0..051f839994 100644
--- a/activesupport/test/autoloading_fixtures/raises_name_error.rb
+++ b/activesupport/test/autoloading_fixtures/raises_name_error.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class RaisesNameError
   FooBarBaz
 end
diff --git a/activesupport/test/autoloading_fixtures/raises_no_method_error.rb b/activesupport/test/autoloading_fixtures/raises_no_method_error.rb
index e1b8fce24a..1db51879c7 100644
--- a/activesupport/test/autoloading_fixtures/raises_no_method_error.rb
+++ b/activesupport/test/autoloading_fixtures/raises_no_method_error.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class RaisesNoMethodError
   self.foobar_method_doesnt_exist
 end
diff --git a/activesupport/test/autoloading_fixtures/requires_constant.rb b/activesupport/test/autoloading_fixtures/requires_constant.rb
index f04dcc4091..a26e265f71 100644
--- a/activesupport/test/autoloading_fixtures/requires_constant.rb
+++ b/activesupport/test/autoloading_fixtures/requires_constant.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "loaded_constant"
 
 module RequiresConstant
diff --git a/activesupport/test/autoloading_fixtures/should_not_be_required.rb b/activesupport/test/autoloading_fixtures/should_not_be_required.rb
index 1fcf170cc5..c1fada8213 100644
--- a/activesupport/test/autoloading_fixtures/should_not_be_required.rb
+++ b/activesupport/test/autoloading_fixtures/should_not_be_required.rb
@@ -1 +1,2 @@
+# frozen_string_literal: true
 ShouldNotBeAutoloaded = 0
diff --git a/activesupport/test/autoloading_fixtures/throws.rb b/activesupport/test/autoloading_fixtures/throws.rb
index e1d96cc512..431111afbe 100644
--- a/activesupport/test/autoloading_fixtures/throws.rb
+++ b/activesupport/test/autoloading_fixtures/throws.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 Throws = 1
 _ = A::B # Autoloading recursion, expected to be discarded.
 
diff --git a/activesupport/test/autoloading_fixtures/typo.rb b/activesupport/test/autoloading_fixtures/typo.rb
index 0ffe07c2b3..0b74d73f3f 100644
--- a/activesupport/test/autoloading_fixtures/typo.rb
+++ b/activesupport/test/autoloading_fixtures/typo.rb
@@ -1 +1,2 @@
+# frozen_string_literal: true
 TypO = 1
diff --git a/activesupport/test/benchmarkable_test.rb b/activesupport/test/benchmarkable_test.rb
index 210b9cb9fd..cb8cb89a30 100644
--- a/activesupport/test/benchmarkable_test.rb
+++ b/activesupport/test/benchmarkable_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class BenchmarkableTest < ActiveSupport::TestCase
diff --git a/activesupport/test/broadcast_logger_test.rb b/activesupport/test/broadcast_logger_test.rb
index 184d0ebddd..c91e3f770f 100644
--- a/activesupport/test/broadcast_logger_test.rb
+++ b/activesupport/test/broadcast_logger_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 module ActiveSupport
diff --git a/activesupport/test/cache/behaviors.rb b/activesupport/test/cache/behaviors.rb
index efd045ac5e..c94cbc1156 100644
--- a/activesupport/test/cache/behaviors.rb
+++ b/activesupport/test/cache/behaviors.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "behaviors/autoloading_cache_behavior"
 require_relative "behaviors/cache_delete_matched_behavior"
 require_relative "behaviors/cache_increment_decrement_behavior"
diff --git a/activesupport/test/cache/behaviors/autoloading_cache_behavior.rb b/activesupport/test/cache/behaviors/autoloading_cache_behavior.rb
index 5f8af331f6..41a3a873b6 100644
--- a/activesupport/test/cache/behaviors/autoloading_cache_behavior.rb
+++ b/activesupport/test/cache/behaviors/autoloading_cache_behavior.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "dependencies_test_helpers"
 
 module AutoloadingCacheBehavior
diff --git a/activesupport/test/cache/behaviors/cache_delete_matched_behavior.rb b/activesupport/test/cache/behaviors/cache_delete_matched_behavior.rb
index b872eb0279..b2cd919da9 100644
--- a/activesupport/test/cache/behaviors/cache_delete_matched_behavior.rb
+++ b/activesupport/test/cache/behaviors/cache_delete_matched_behavior.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module CacheDeleteMatchedBehavior
   def test_delete_matched
     @cache.write("foo", "bar")
diff --git a/activesupport/test/cache/behaviors/cache_increment_decrement_behavior.rb b/activesupport/test/cache/behaviors/cache_increment_decrement_behavior.rb
index 0d32339565..45f92f10b2 100644
--- a/activesupport/test/cache/behaviors/cache_increment_decrement_behavior.rb
+++ b/activesupport/test/cache/behaviors/cache_increment_decrement_behavior.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module CacheIncrementDecrementBehavior
   def test_increment
     @cache.write("foo", 1, raw: true)
diff --git a/activesupport/test/cache/behaviors/cache_store_behavior.rb b/activesupport/test/cache/behaviors/cache_store_behavior.rb
index 4631e6aee8..32373644cf 100644
--- a/activesupport/test/cache/behaviors/cache_store_behavior.rb
+++ b/activesupport/test/cache/behaviors/cache_store_behavior.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # Tests the base functionality that should be identical across all cache stores.
 module CacheStoreBehavior
   def test_should_read_and_write_strings
diff --git a/activesupport/test/cache/behaviors/cache_store_version_behavior.rb b/activesupport/test/cache/behaviors/cache_store_version_behavior.rb
index a0170c896f..82f392c86a 100644
--- a/activesupport/test/cache/behaviors/cache_store_version_behavior.rb
+++ b/activesupport/test/cache/behaviors/cache_store_version_behavior.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module CacheStoreVersionBehavior
   ModelWithKeyAndVersion = Struct.new(:cache_key, :cache_version)
 
diff --git a/activesupport/test/cache/behaviors/encoded_key_cache_behavior.rb b/activesupport/test/cache/behaviors/encoded_key_cache_behavior.rb
index 6adef2916d..361903ab82 100644
--- a/activesupport/test/cache/behaviors/encoded_key_cache_behavior.rb
+++ b/activesupport/test/cache/behaviors/encoded_key_cache_behavior.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # https://rails.lighthouseapp.com/projects/8994/tickets/6225-memcachestore-cant-deal-with-umlauts-and-special-characters
 # The error is caused by character encodings that can't be compared with ASCII-8BIT regular expressions and by special
 # characters like the umlaut in UTF-8.
diff --git a/activesupport/test/cache/behaviors/local_cache_behavior.rb b/activesupport/test/cache/behaviors/local_cache_behavior.rb
index 8530296374..730f0306b8 100644
--- a/activesupport/test/cache/behaviors/local_cache_behavior.rb
+++ b/activesupport/test/cache/behaviors/local_cache_behavior.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module LocalCacheBehavior
   def test_local_writes_are_persistent_on_the_remote_cache
     retval = @cache.with_local_cache do
diff --git a/activesupport/test/cache/cache_entry_test.rb b/activesupport/test/cache/cache_entry_test.rb
index e446e39b10..4a8fc5bed3 100644
--- a/activesupport/test/cache/cache_entry_test.rb
+++ b/activesupport/test/cache/cache_entry_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/cache"
 
diff --git a/activesupport/test/cache/cache_key_test.rb b/activesupport/test/cache/cache_key_test.rb
index ea39d7a299..19c40d44d6 100644
--- a/activesupport/test/cache/cache_key_test.rb
+++ b/activesupport/test/cache/cache_key_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/cache"
 
diff --git a/activesupport/test/cache/cache_store_logger_test.rb b/activesupport/test/cache/cache_store_logger_test.rb
index 621cfebb10..3014c4d57f 100644
--- a/activesupport/test/cache/cache_store_logger_test.rb
+++ b/activesupport/test/cache/cache_store_logger_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/cache"
 
diff --git a/activesupport/test/cache/cache_store_namespace_test.rb b/activesupport/test/cache/cache_store_namespace_test.rb
index e395c88271..8df048aad0 100644
--- a/activesupport/test/cache/cache_store_namespace_test.rb
+++ b/activesupport/test/cache/cache_store_namespace_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/cache"
 
diff --git a/activesupport/test/cache/cache_store_setting_test.rb b/activesupport/test/cache/cache_store_setting_test.rb
index cb9b006abe..cc126ec930 100644
--- a/activesupport/test/cache/cache_store_setting_test.rb
+++ b/activesupport/test/cache/cache_store_setting_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/cache"
 require "dalli"
diff --git a/activesupport/test/cache/cache_store_write_multi_test.rb b/activesupport/test/cache/cache_store_write_multi_test.rb
index 16e3f3b842..9355dde0f4 100644
--- a/activesupport/test/cache/cache_store_write_multi_test.rb
+++ b/activesupport/test/cache/cache_store_write_multi_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/cache"
 
diff --git a/activesupport/test/cache/local_cache_middleware_test.rb b/activesupport/test/cache/local_cache_middleware_test.rb
index 352502fb43..3f0bd40fbd 100644
--- a/activesupport/test/cache/local_cache_middleware_test.rb
+++ b/activesupport/test/cache/local_cache_middleware_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/cache"
 
diff --git a/activesupport/test/cache/stores/file_store_test.rb b/activesupport/test/cache/stores/file_store_test.rb
index 48b304fe6e..6ba25bbaec 100644
--- a/activesupport/test/cache/stores/file_store_test.rb
+++ b/activesupport/test/cache/stores/file_store_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/cache"
 require_relative "../behaviors"
diff --git a/activesupport/test/cache/stores/mem_cache_store_test.rb b/activesupport/test/cache/stores/mem_cache_store_test.rb
index 2dd5264818..e188f5f881 100644
--- a/activesupport/test/cache/stores/mem_cache_store_test.rb
+++ b/activesupport/test/cache/stores/mem_cache_store_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/cache"
 require_relative "../behaviors"
diff --git a/activesupport/test/cache/stores/memory_store_test.rb b/activesupport/test/cache/stores/memory_store_test.rb
index 3dd1646d56..e8dfe24a2f 100644
--- a/activesupport/test/cache/stores/memory_store_test.rb
+++ b/activesupport/test/cache/stores/memory_store_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/cache"
 require_relative "../behaviors"
diff --git a/activesupport/test/cache/stores/null_store_test.rb b/activesupport/test/cache/stores/null_store_test.rb
index 23c4e64ee4..0945aceee3 100644
--- a/activesupport/test/cache/stores/null_store_test.rb
+++ b/activesupport/test/cache/stores/null_store_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/cache"
 require_relative "../behaviors"
diff --git a/activesupport/test/callback_inheritance_test.rb b/activesupport/test/callback_inheritance_test.rb
index 9e2f7527e0..8872a16282 100644
--- a/activesupport/test/callback_inheritance_test.rb
+++ b/activesupport/test/callback_inheritance_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class GrandParent
diff --git a/activesupport/test/callbacks_test.rb b/activesupport/test/callbacks_test.rb
index 4f00afb581..9d924cabb2 100644
--- a/activesupport/test/callbacks_test.rb
+++ b/activesupport/test/callbacks_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 module CallbacksTest
diff --git a/activesupport/test/class_cache_test.rb b/activesupport/test/class_cache_test.rb
index 004b4dc9ce..b3ca3748c2 100644
--- a/activesupport/test/class_cache_test.rb
+++ b/activesupport/test/class_cache_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/dependencies"
 
diff --git a/activesupport/test/clean_backtrace_test.rb b/activesupport/test/clean_backtrace_test.rb
index 5ed518cdb0..7bbc54dfcc 100644
--- a/activesupport/test/clean_backtrace_test.rb
+++ b/activesupport/test/clean_backtrace_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class BacktraceCleanerFilterTest < ActiveSupport::TestCase
diff --git a/activesupport/test/clean_logger_test.rb b/activesupport/test/clean_logger_test.rb
index cf37fc5639..923a1cb671 100644
--- a/activesupport/test/clean_logger_test.rb
+++ b/activesupport/test/clean_logger_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "stringio"
 require "active_support/logger"
diff --git a/activesupport/test/concern_test.rb b/activesupport/test/concern_test.rb
index 7a5a5414a7..e05704393d 100644
--- a/activesupport/test/concern_test.rb
+++ b/activesupport/test/concern_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/concern"
 
diff --git a/activesupport/test/configurable_test.rb b/activesupport/test/configurable_test.rb
index 3cd6d2d4d0..bd3452334a 100644
--- a/activesupport/test/configurable_test.rb
+++ b/activesupport/test/configurable_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/configurable"
 
diff --git a/activesupport/test/constantize_test_cases.rb b/activesupport/test/constantize_test_cases.rb
index 32b720bcbb..fa23fd6b65 100644
--- a/activesupport/test/constantize_test_cases.rb
+++ b/activesupport/test/constantize_test_cases.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "dependencies_test_helpers"
 
 module Ace
diff --git a/activesupport/test/core_ext/array/access_test.rb b/activesupport/test/core_ext/array/access_test.rb
index a38ea36d00..08af9e1b55 100644
--- a/activesupport/test/core_ext/array/access_test.rb
+++ b/activesupport/test/core_ext/array/access_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/array"
 
diff --git a/activesupport/test/core_ext/array/conversions_test.rb b/activesupport/test/core_ext/array/conversions_test.rb
index bbe81ae70c..5a073344d9 100644
--- a/activesupport/test/core_ext/array/conversions_test.rb
+++ b/activesupport/test/core_ext/array/conversions_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/array"
 require "active_support/core_ext/big_decimal"
diff --git a/activesupport/test/core_ext/array/extract_options_test.rb b/activesupport/test/core_ext/array/extract_options_test.rb
index 1651bee0f6..09bf97ae6c 100644
--- a/activesupport/test/core_ext/array/extract_options_test.rb
+++ b/activesupport/test/core_ext/array/extract_options_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/array"
 require "active_support/core_ext/hash"
diff --git a/activesupport/test/core_ext/array/grouping_test.rb b/activesupport/test/core_ext/array/grouping_test.rb
index 4c6aadba8c..daf47e9a9f 100644
--- a/activesupport/test/core_ext/array/grouping_test.rb
+++ b/activesupport/test/core_ext/array/grouping_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/array"
 
diff --git a/activesupport/test/core_ext/array/prepend_append_test.rb b/activesupport/test/core_ext/array/prepend_append_test.rb
index 763e26191d..3b38acf56c 100644
--- a/activesupport/test/core_ext/array/prepend_append_test.rb
+++ b/activesupport/test/core_ext/array/prepend_append_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/array"
 
diff --git a/activesupport/test/core_ext/array/wrap_test.rb b/activesupport/test/core_ext/array/wrap_test.rb
index ae846cb3f2..451f9db2ed 100644
--- a/activesupport/test/core_ext/array/wrap_test.rb
+++ b/activesupport/test/core_ext/array/wrap_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/array"
 
diff --git a/activesupport/test/core_ext/bigdecimal_test.rb b/activesupport/test/core_ext/bigdecimal_test.rb
index 43b659546f..dbd0762574 100644
--- a/activesupport/test/core_ext/bigdecimal_test.rb
+++ b/activesupport/test/core_ext/bigdecimal_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/big_decimal"
 
diff --git a/activesupport/test/core_ext/class/attribute_test.rb b/activesupport/test/core_ext/class/attribute_test.rb
index f16043c612..2933b62c58 100644
--- a/activesupport/test/core_ext/class/attribute_test.rb
+++ b/activesupport/test/core_ext/class/attribute_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/class/attribute"
 
diff --git a/activesupport/test/core_ext/class_test.rb b/activesupport/test/core_ext/class_test.rb
index a7905196ae..c0cabea8fd 100644
--- a/activesupport/test/core_ext/class_test.rb
+++ b/activesupport/test/core_ext/class_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/class"
 require "set"
diff --git a/activesupport/test/core_ext/date_and_time_behavior.rb b/activesupport/test/core_ext/date_and_time_behavior.rb
index 6c77e8f313..8d908968ef 100644
--- a/activesupport/test/core_ext/date_and_time_behavior.rb
+++ b/activesupport/test/core_ext/date_and_time_behavior.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 module DateAndTimeBehavior
diff --git a/activesupport/test/core_ext/date_and_time_compatibility_test.rb b/activesupport/test/core_ext/date_and_time_compatibility_test.rb
index 6c6205a4d2..04b93105d5 100644
--- a/activesupport/test/core_ext/date_and_time_compatibility_test.rb
+++ b/activesupport/test/core_ext/date_and_time_compatibility_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/time"
 require "time_zone_test_helpers"
diff --git a/activesupport/test/core_ext/date_ext_test.rb b/activesupport/test/core_ext/date_ext_test.rb
index 50bb1004f7..7c6e705936 100644
--- a/activesupport/test/core_ext/date_ext_test.rb
+++ b/activesupport/test/core_ext/date_ext_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/time"
 require "core_ext/date_and_time_behavior"
diff --git a/activesupport/test/core_ext/date_time_ext_test.rb b/activesupport/test/core_ext/date_time_ext_test.rb
index 276fa2bfd3..beddfe4584 100644
--- a/activesupport/test/core_ext/date_time_ext_test.rb
+++ b/activesupport/test/core_ext/date_time_ext_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/time"
 require "core_ext/date_and_time_behavior"
diff --git a/activesupport/test/core_ext/digest/uuid_test.rb b/activesupport/test/core_ext/digest/uuid_test.rb
index 866a03259a..ea3605bf9c 100644
--- a/activesupport/test/core_ext/digest/uuid_test.rb
+++ b/activesupport/test/core_ext/digest/uuid_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/digest/uuid"
 
diff --git a/activesupport/test/core_ext/duration_test.rb b/activesupport/test/core_ext/duration_test.rb
index cd1b505c34..32c0ce4317 100644
--- a/activesupport/test/core_ext/duration_test.rb
+++ b/activesupport/test/core_ext/duration_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/inflector"
 require "active_support/time"
diff --git a/activesupport/test/core_ext/enumerable_test.rb b/activesupport/test/core_ext/enumerable_test.rb
index 0b345ecf0f..3259109b0e 100644
--- a/activesupport/test/core_ext/enumerable_test.rb
+++ b/activesupport/test/core_ext/enumerable_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/array"
 require "active_support/core_ext/enumerable"
diff --git a/activesupport/test/core_ext/file_test.rb b/activesupport/test/core_ext/file_test.rb
index df5d09acd0..67b1a04429 100644
--- a/activesupport/test/core_ext/file_test.rb
+++ b/activesupport/test/core_ext/file_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/file"
 
diff --git a/activesupport/test/core_ext/hash/transform_keys_test.rb b/activesupport/test/core_ext/hash/transform_keys_test.rb
index 7a11d827f8..f329246bdd 100644
--- a/activesupport/test/core_ext/hash/transform_keys_test.rb
+++ b/activesupport/test/core_ext/hash/transform_keys_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/hash/keys"
 
diff --git a/activesupport/test/core_ext/hash/transform_values_test.rb b/activesupport/test/core_ext/hash/transform_values_test.rb
index f2ac4ce6ce..4eb6999510 100644
--- a/activesupport/test/core_ext/hash/transform_values_test.rb
+++ b/activesupport/test/core_ext/hash/transform_values_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/hash/indifferent_access"
 require "active_support/core_ext/hash/transform_values"
diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb
index 18da5fcf5f..c533c002a4 100644
--- a/activesupport/test/core_ext/hash_ext_test.rb
+++ b/activesupport/test/core_ext/hash_ext_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/hash"
 require "bigdecimal"
diff --git a/activesupport/test/core_ext/integer_ext_test.rb b/activesupport/test/core_ext/integer_ext_test.rb
index 137e8ce85f..a7ea084e7f 100644
--- a/activesupport/test/core_ext/integer_ext_test.rb
+++ b/activesupport/test/core_ext/integer_ext_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/integer"
 
diff --git a/activesupport/test/core_ext/kernel/concern_test.rb b/activesupport/test/core_ext/kernel/concern_test.rb
index e7e4f99d7e..1f4fb8029c 100644
--- a/activesupport/test/core_ext/kernel/concern_test.rb
+++ b/activesupport/test/core_ext/kernel/concern_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/kernel/concern"
 
diff --git a/activesupport/test/core_ext/kernel_test.rb b/activesupport/test/core_ext/kernel_test.rb
index 26f5088ede..875598f611 100644
--- a/activesupport/test/core_ext/kernel_test.rb
+++ b/activesupport/test/core_ext/kernel_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/kernel"
 
diff --git a/activesupport/test/core_ext/load_error_test.rb b/activesupport/test/core_ext/load_error_test.rb
index 44ff6bb051..3d003fd1d5 100644
--- a/activesupport/test/core_ext/load_error_test.rb
+++ b/activesupport/test/core_ext/load_error_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/load_error"
 
diff --git a/activesupport/test/core_ext/marshal_test.rb b/activesupport/test/core_ext/marshal_test.rb
index cabeed2fae..d17a6fe7f1 100644
--- a/activesupport/test/core_ext/marshal_test.rb
+++ b/activesupport/test/core_ext/marshal_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/marshal"
 require "dependencies_test_helpers"
diff --git a/activesupport/test/core_ext/module/anonymous_test.rb b/activesupport/test/core_ext/module/anonymous_test.rb
index f885444284..d667bc0a34 100644
--- a/activesupport/test/core_ext/module/anonymous_test.rb
+++ b/activesupport/test/core_ext/module/anonymous_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/module/anonymous"
 
diff --git a/activesupport/test/core_ext/module/attr_internal_test.rb b/activesupport/test/core_ext/module/attr_internal_test.rb
index 8458e278ee..12dc2f101a 100644
--- a/activesupport/test/core_ext/module/attr_internal_test.rb
+++ b/activesupport/test/core_ext/module/attr_internal_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/module/attr_internal"
 
diff --git a/activesupport/test/core_ext/module/attribute_accessor_per_thread_test.rb b/activesupport/test/core_ext/module/attribute_accessor_per_thread_test.rb
index af240bc38d..e8587e3424 100644
--- a/activesupport/test/core_ext/module/attribute_accessor_per_thread_test.rb
+++ b/activesupport/test/core_ext/module/attribute_accessor_per_thread_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/module/attribute_accessors_per_thread"
 
diff --git a/activesupport/test/core_ext/module/attribute_accessor_test.rb b/activesupport/test/core_ext/module/attribute_accessor_test.rb
index 9b185e9381..2cf33fcc12 100644
--- a/activesupport/test/core_ext/module/attribute_accessor_test.rb
+++ b/activesupport/test/core_ext/module/attribute_accessor_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/module/attribute_accessors"
 
diff --git a/activesupport/test/core_ext/module/attribute_aliasing_test.rb b/activesupport/test/core_ext/module/attribute_aliasing_test.rb
index fdfa868851..9e5edda77a 100644
--- a/activesupport/test/core_ext/module/attribute_aliasing_test.rb
+++ b/activesupport/test/core_ext/module/attribute_aliasing_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/module/aliasing"
 
diff --git a/activesupport/test/core_ext/module/concerning_test.rb b/activesupport/test/core_ext/module/concerning_test.rb
index 098036828a..64accc06fc 100644
--- a/activesupport/test/core_ext/module/concerning_test.rb
+++ b/activesupport/test/core_ext/module/concerning_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/module/concerning"
 
diff --git a/activesupport/test/core_ext/module/introspection_test.rb b/activesupport/test/core_ext/module/introspection_test.rb
index db383850cd..589c9455ed 100644
--- a/activesupport/test/core_ext/module/introspection_test.rb
+++ b/activesupport/test/core_ext/module/introspection_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/module/introspection"
 
diff --git a/activesupport/test/core_ext/module/reachable_test.rb b/activesupport/test/core_ext/module/reachable_test.rb
index 487c7dee16..f8970bc9f4 100644
--- a/activesupport/test/core_ext/module/reachable_test.rb
+++ b/activesupport/test/core_ext/module/reachable_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/module/reachable"
 
diff --git a/activesupport/test/core_ext/module/remove_method_test.rb b/activesupport/test/core_ext/module/remove_method_test.rb
index 0c627f1e74..327c66e3ec 100644
--- a/activesupport/test/core_ext/module/remove_method_test.rb
+++ b/activesupport/test/core_ext/module/remove_method_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/module/remove_method"
 
diff --git a/activesupport/test/core_ext/module_test.rb b/activesupport/test/core_ext/module_test.rb
index a4d4444d69..b683c4e110 100644
--- a/activesupport/test/core_ext/module_test.rb
+++ b/activesupport/test/core_ext/module_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/module"
 
diff --git a/activesupport/test/core_ext/name_error_test.rb b/activesupport/test/core_ext/name_error_test.rb
index fdb9493d3c..a99b20602d 100644
--- a/activesupport/test/core_ext/name_error_test.rb
+++ b/activesupport/test/core_ext/name_error_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/name_error"
 
diff --git a/activesupport/test/core_ext/numeric_ext_test.rb b/activesupport/test/core_ext/numeric_ext_test.rb
index 3cfbe6e7e6..d4e03a90a4 100644
--- a/activesupport/test/core_ext/numeric_ext_test.rb
+++ b/activesupport/test/core_ext/numeric_ext_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/time"
 require "active_support/core_ext/numeric"
diff --git a/activesupport/test/core_ext/object/acts_like_test.rb b/activesupport/test/core_ext/object/acts_like_test.rb
index 631f4e63a8..1f1b71f748 100644
--- a/activesupport/test/core_ext/object/acts_like_test.rb
+++ b/activesupport/test/core_ext/object/acts_like_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/object"
 
diff --git a/activesupport/test/core_ext/object/blank_test.rb b/activesupport/test/core_ext/object/blank_test.rb
index 7fd3fed042..fbd96893f6 100644
--- a/activesupport/test/core_ext/object/blank_test.rb
+++ b/activesupport/test/core_ext/object/blank_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/object/blank"
 
diff --git a/activesupport/test/core_ext/object/deep_dup_test.rb b/activesupport/test/core_ext/object/deep_dup_test.rb
index f247ee16de..d6f0a71c5b 100644
--- a/activesupport/test/core_ext/object/deep_dup_test.rb
+++ b/activesupport/test/core_ext/object/deep_dup_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/object"
 
diff --git a/activesupport/test/core_ext/object/duplicable_test.rb b/activesupport/test/core_ext/object/duplicable_test.rb
index 68b0129980..7607e98b0c 100644
--- a/activesupport/test/core_ext/object/duplicable_test.rb
+++ b/activesupport/test/core_ext/object/duplicable_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "bigdecimal"
 require "active_support/core_ext/object/duplicable"
diff --git a/activesupport/test/core_ext/object/inclusion_test.rb b/activesupport/test/core_ext/object/inclusion_test.rb
index 955686d6aa..b706e6b90f 100644
--- a/activesupport/test/core_ext/object/inclusion_test.rb
+++ b/activesupport/test/core_ext/object/inclusion_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/object/inclusion"
 
diff --git a/activesupport/test/core_ext/object/instance_variables_test.rb b/activesupport/test/core_ext/object/instance_variables_test.rb
index 5bdb2fbc35..df38282fb0 100644
--- a/activesupport/test/core_ext/object/instance_variables_test.rb
+++ b/activesupport/test/core_ext/object/instance_variables_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/object"
 
diff --git a/activesupport/test/core_ext/object/json_cherry_pick_test.rb b/activesupport/test/core_ext/object/json_cherry_pick_test.rb
index dd4e90918e..9f3f92a74b 100644
--- a/activesupport/test/core_ext/object/json_cherry_pick_test.rb
+++ b/activesupport/test/core_ext/object/json_cherry_pick_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 # These test cases were added to test that cherry-picking the json extensions
diff --git a/activesupport/test/core_ext/object/json_gem_encoding_test.rb b/activesupport/test/core_ext/object/json_gem_encoding_test.rb
index f5016d0c2a..3ff34e448e 100644
--- a/activesupport/test/core_ext/object/json_gem_encoding_test.rb
+++ b/activesupport/test/core_ext/object/json_gem_encoding_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "json"
 require "json/encoding_test_cases"
diff --git a/activesupport/test/core_ext/object/to_param_test.rb b/activesupport/test/core_ext/object/to_param_test.rb
index 56246b24f3..e446092abe 100644
--- a/activesupport/test/core_ext/object/to_param_test.rb
+++ b/activesupport/test/core_ext/object/to_param_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/object/to_param"
 
diff --git a/activesupport/test/core_ext/object/to_query_test.rb b/activesupport/test/core_ext/object/to_query_test.rb
index 298c8bf373..44147d47cf 100644
--- a/activesupport/test/core_ext/object/to_query_test.rb
+++ b/activesupport/test/core_ext/object/to_query_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/ordered_hash"
 require "active_support/core_ext/object/to_query"
diff --git a/activesupport/test/core_ext/object/try_test.rb b/activesupport/test/core_ext/object/try_test.rb
index 5c8bf59952..fe437f6260 100644
--- a/activesupport/test/core_ext/object/try_test.rb
+++ b/activesupport/test/core_ext/object/try_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/object"
 
diff --git a/activesupport/test/core_ext/range_ext_test.rb b/activesupport/test/core_ext/range_ext_test.rb
index d166c7309c..693de2755d 100644
--- a/activesupport/test/core_ext/range_ext_test.rb
+++ b/activesupport/test/core_ext/range_ext_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/time"
 require "active_support/core_ext/numeric"
diff --git a/activesupport/test/core_ext/regexp_ext_test.rb b/activesupport/test/core_ext/regexp_ext_test.rb
index e569a9f234..c937dad1db 100644
--- a/activesupport/test/core_ext/regexp_ext_test.rb
+++ b/activesupport/test/core_ext/regexp_ext_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/regexp"
 
diff --git a/activesupport/test/core_ext/secure_random_test.rb b/activesupport/test/core_ext/secure_random_test.rb
index fc25f6ab41..b2ac4640ab 100644
--- a/activesupport/test/core_ext/secure_random_test.rb
+++ b/activesupport/test/core_ext/secure_random_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/securerandom"
 
diff --git a/activesupport/test/core_ext/string_ext_test.rb b/activesupport/test/core_ext/string_ext_test.rb
index daa8c3f2ef..defec8bba0 100644
--- a/activesupport/test/core_ext/string_ext_test.rb
+++ b/activesupport/test/core_ext/string_ext_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "date"
 require "abstract_unit"
 require "timeout"
diff --git a/activesupport/test/core_ext/time_ext_test.rb b/activesupport/test/core_ext/time_ext_test.rb
index 625a5bffb8..f1c6fa4f8c 100644
--- a/activesupport/test/core_ext/time_ext_test.rb
+++ b/activesupport/test/core_ext/time_ext_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/time"
 require "core_ext/date_and_time_behavior"
diff --git a/activesupport/test/core_ext/time_with_zone_test.rb b/activesupport/test/core_ext/time_with_zone_test.rb
index 70ae793cda..9401b9be07 100644
--- a/activesupport/test/core_ext/time_with_zone_test.rb
+++ b/activesupport/test/core_ext/time_with_zone_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/time"
 require "time_zone_test_helpers"
diff --git a/activesupport/test/core_ext/uri_ext_test.rb b/activesupport/test/core_ext/uri_ext_test.rb
index 0f13ca9c0e..555716d1c3 100644
--- a/activesupport/test/core_ext/uri_ext_test.rb
+++ b/activesupport/test/core_ext/uri_ext_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "uri"
 require "active_support/core_ext/uri"
diff --git a/activesupport/test/current_attributes_test.rb b/activesupport/test/current_attributes_test.rb
index 67ef6ef619..f195787135 100644
--- a/activesupport/test/current_attributes_test.rb
+++ b/activesupport/test/current_attributes_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class CurrentAttributesTest < ActiveSupport::TestCase
diff --git a/activesupport/test/dependencies/check_warnings.rb b/activesupport/test/dependencies/check_warnings.rb
index 03c3dca1d6..d177dce295 100644
--- a/activesupport/test/dependencies/check_warnings.rb
+++ b/activesupport/test/dependencies/check_warnings.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 $check_warnings_load_count += 1
 $checked_verbose = $VERBOSE
diff --git a/activesupport/test/dependencies/conflict.rb b/activesupport/test/dependencies/conflict.rb
index 7eff49bbfa..a7199a093b 100644
--- a/activesupport/test/dependencies/conflict.rb
+++ b/activesupport/test/dependencies/conflict.rb
@@ -1 +1,2 @@
+# frozen_string_literal: true
 Conflict = 1
diff --git a/activesupport/test/dependencies/cross_site_depender.rb b/activesupport/test/dependencies/cross_site_depender.rb
index fbc3b64f56..b414058e27 100644
--- a/activesupport/test/dependencies/cross_site_depender.rb
+++ b/activesupport/test/dependencies/cross_site_depender.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 class CrossSiteDepender
   CrossSiteDependency
 end
diff --git a/activesupport/test/dependencies/mutual_one.rb b/activesupport/test/dependencies/mutual_one.rb
index 05f08f82d3..f739ce2744 100644
--- a/activesupport/test/dependencies/mutual_one.rb
+++ b/activesupport/test/dependencies/mutual_one.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 $mutual_dependencies_count += 1
 require_dependency "mutual_two"
 require_dependency "mutual_two.rb"
diff --git a/activesupport/test/dependencies/mutual_two.rb b/activesupport/test/dependencies/mutual_two.rb
index 1d87d334af..30034be6d1 100644
--- a/activesupport/test/dependencies/mutual_two.rb
+++ b/activesupport/test/dependencies/mutual_two.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 $mutual_dependencies_count += 1
 require_dependency "mutual_one.rb"
 require_dependency "mutual_one"
diff --git a/activesupport/test/dependencies/raises_exception.rb b/activesupport/test/dependencies/raises_exception.rb
index 0a56680fe3..ce9050e572 100644
--- a/activesupport/test/dependencies/raises_exception.rb
+++ b/activesupport/test/dependencies/raises_exception.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 $raises_exception_load_count += 1
 raise Exception, "Loading me failed, so do not add to loaded or history."
 $raises_exception_load_count += 1
diff --git a/activesupport/test/dependencies/raises_exception_without_blame_file.rb b/activesupport/test/dependencies/raises_exception_without_blame_file.rb
index 7c3856b1e6..7fb2a5c8bc 100644
--- a/activesupport/test/dependencies/raises_exception_without_blame_file.rb
+++ b/activesupport/test/dependencies/raises_exception_without_blame_file.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 exception = Exception.new("I am not blamable!")
 class << exception
   undef_method(:blame_file!)
diff --git a/activesupport/test/dependencies/requires_nonexistent0.rb b/activesupport/test/dependencies/requires_nonexistent0.rb
index 7f8a0d8419..86a66203f8 100644
--- a/activesupport/test/dependencies/requires_nonexistent0.rb
+++ b/activesupport/test/dependencies/requires_nonexistent0.rb
@@ -1 +1,2 @@
+# frozen_string_literal: true
 require "RMagickDontExistDude"
diff --git a/activesupport/test/dependencies/requires_nonexistent1.rb b/activesupport/test/dependencies/requires_nonexistent1.rb
index 0055177d67..a3ec7ce4ef 100644
--- a/activesupport/test/dependencies/requires_nonexistent1.rb
+++ b/activesupport/test/dependencies/requires_nonexistent1.rb
@@ -1 +1,2 @@
+# frozen_string_literal: true
 require_dependency "requires_nonexistent0"
diff --git a/activesupport/test/dependencies/service_one.rb b/activesupport/test/dependencies/service_one.rb
index afc3042269..6149297741 100644
--- a/activesupport/test/dependencies/service_one.rb
+++ b/activesupport/test/dependencies/service_one.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 $loaded_service_one ||= 0
 $loaded_service_one += 1
 
diff --git a/activesupport/test/dependencies/service_two.rb b/activesupport/test/dependencies/service_two.rb
index aabfc3c553..4c013f1fe3 100644
--- a/activesupport/test/dependencies/service_two.rb
+++ b/activesupport/test/dependencies/service_two.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class ServiceTwo
 end
diff --git a/activesupport/test/dependencies_test.rb b/activesupport/test/dependencies_test.rb
index 1ea36418ff..1aad7fc0ec 100644
--- a/activesupport/test/dependencies_test.rb
+++ b/activesupport/test/dependencies_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "pp"
 require "active_support/dependencies"
diff --git a/activesupport/test/dependencies_test_helpers.rb b/activesupport/test/dependencies_test_helpers.rb
index 451195a143..9ba8f3b9b5 100644
--- a/activesupport/test/dependencies_test_helpers.rb
+++ b/activesupport/test/dependencies_test_helpers.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module DependenciesTestHelpers
   def with_loading(*from)
     old_mechanism, ActiveSupport::Dependencies.mechanism = ActiveSupport::Dependencies.mechanism, :load
diff --git a/activesupport/test/deprecation/method_wrappers_test.rb b/activesupport/test/deprecation/method_wrappers_test.rb
index 85d057bb02..33ce4aaeca 100644
--- a/activesupport/test/deprecation/method_wrappers_test.rb
+++ b/activesupport/test/deprecation/method_wrappers_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/deprecation"
 
diff --git a/activesupport/test/deprecation/proxy_wrappers_test.rb b/activesupport/test/deprecation/proxy_wrappers_test.rb
index 67afd75c44..ff38a8165d 100644
--- a/activesupport/test/deprecation/proxy_wrappers_test.rb
+++ b/activesupport/test/deprecation/proxy_wrappers_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/deprecation"
 
diff --git a/activesupport/test/deprecation_test.rb b/activesupport/test/deprecation_test.rb
index 257cb50fb2..22e0ef9afc 100644
--- a/activesupport/test/deprecation_test.rb
+++ b/activesupport/test/deprecation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/testing/stream"
 
diff --git a/activesupport/test/descendants_tracker_test_cases.rb b/activesupport/test/descendants_tracker_test_cases.rb
index cf349d53ee..abae3f5880 100644
--- a/activesupport/test/descendants_tracker_test_cases.rb
+++ b/activesupport/test/descendants_tracker_test_cases.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "set"
 
 module DescendantsTrackerTestCases
diff --git a/activesupport/test/descendants_tracker_with_autoloading_test.rb b/activesupport/test/descendants_tracker_with_autoloading_test.rb
index e202667a8a..021093956f 100644
--- a/activesupport/test/descendants_tracker_with_autoloading_test.rb
+++ b/activesupport/test/descendants_tracker_with_autoloading_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/descendants_tracker"
 require "active_support/dependencies"
diff --git a/activesupport/test/descendants_tracker_without_autoloading_test.rb b/activesupport/test/descendants_tracker_without_autoloading_test.rb
index 72adc30ace..cadd21be92 100644
--- a/activesupport/test/descendants_tracker_without_autoloading_test.rb
+++ b/activesupport/test/descendants_tracker_without_autoloading_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/descendants_tracker"
 require "descendants_tracker_test_cases"
diff --git a/activesupport/test/evented_file_update_checker_test.rb b/activesupport/test/evented_file_update_checker_test.rb
index f33a5f5764..9450bcb814 100644
--- a/activesupport/test/evented_file_update_checker_test.rb
+++ b/activesupport/test/evented_file_update_checker_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "pathname"
 require "file_update_checker_shared_tests"
diff --git a/activesupport/test/executor_test.rb b/activesupport/test/executor_test.rb
index 7fefc066b3..c522ea9b52 100644
--- a/activesupport/test/executor_test.rb
+++ b/activesupport/test/executor_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class ExecutorTest < ActiveSupport::TestCase
diff --git a/activesupport/test/file_update_checker_shared_tests.rb b/activesupport/test/file_update_checker_shared_tests.rb
index 361e7e2349..90ef886b08 100644
--- a/activesupport/test/file_update_checker_shared_tests.rb
+++ b/activesupport/test/file_update_checker_shared_tests.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "fileutils"
 
 module FileUpdateCheckerSharedTests
diff --git a/activesupport/test/file_update_checker_test.rb b/activesupport/test/file_update_checker_test.rb
index 55b0b46644..5a4e3bebf2 100644
--- a/activesupport/test/file_update_checker_test.rb
+++ b/activesupport/test/file_update_checker_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "file_update_checker_shared_tests"
 
diff --git a/activesupport/test/fixtures/autoload/another_class.rb b/activesupport/test/fixtures/autoload/another_class.rb
index ab6e075ab4..f61698823c 100644
--- a/activesupport/test/fixtures/autoload/another_class.rb
+++ b/activesupport/test/fixtures/autoload/another_class.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class Fixtures::AnotherClass
 end
diff --git a/activesupport/test/fixtures/autoload/some_class.rb b/activesupport/test/fixtures/autoload/some_class.rb
index 30d41eb0bf..a3b5f831ad 100644
--- a/activesupport/test/fixtures/autoload/some_class.rb
+++ b/activesupport/test/fixtures/autoload/some_class.rb
@@ -1,2 +1,3 @@
+# frozen_string_literal: true
 class Fixtures::Autoload::SomeClass
 end
diff --git a/activesupport/test/gzip_test.rb b/activesupport/test/gzip_test.rb
index 33e0cd2a04..592578fedd 100644
--- a/activesupport/test/gzip_test.rb
+++ b/activesupport/test/gzip_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/object/blank"
 
diff --git a/activesupport/test/hash_with_indifferent_access_test.rb b/activesupport/test/hash_with_indifferent_access_test.rb
index d68add46cd..b71839a5a2 100644
--- a/activesupport/test/hash_with_indifferent_access_test.rb
+++ b/activesupport/test/hash_with_indifferent_access_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/hash"
 require "bigdecimal"
diff --git a/activesupport/test/i18n_test.rb b/activesupport/test/i18n_test.rb
index 7d88d2dc6b..58ccbdf108 100644
--- a/activesupport/test/i18n_test.rb
+++ b/activesupport/test/i18n_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/time"
 require "active_support/core_ext/array/conversions"
diff --git a/activesupport/test/inflector_test.rb b/activesupport/test/inflector_test.rb
index ef956eda90..b22054ebee 100644
--- a/activesupport/test/inflector_test.rb
+++ b/activesupport/test/inflector_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/inflector"
 
diff --git a/activesupport/test/inflector_test_cases.rb b/activesupport/test/inflector_test_cases.rb
index d61ca3fc18..9b0d2867c2 100644
--- a/activesupport/test/inflector_test_cases.rb
+++ b/activesupport/test/inflector_test_cases.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module InflectorTestCases
   SingularToPlural = {
     "search"      => "searches",
diff --git a/activesupport/test/json/decoding_test.rb b/activesupport/test/json/decoding_test.rb
index 6f5051c312..52687a003f 100644
--- a/activesupport/test/json/decoding_test.rb
+++ b/activesupport/test/json/decoding_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/json"
 require "active_support/time"
diff --git a/activesupport/test/json/encoding_test.rb b/activesupport/test/json/encoding_test.rb
index 6d8f7cfbd0..314c11b2fc 100644
--- a/activesupport/test/json/encoding_test.rb
+++ b/activesupport/test/json/encoding_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "securerandom"
 require "abstract_unit"
 require "active_support/core_ext/string/inflections"
diff --git a/activesupport/test/json/encoding_test_cases.rb b/activesupport/test/json/encoding_test_cases.rb
index 7e4775cec8..2b64aa624d 100644
--- a/activesupport/test/json/encoding_test_cases.rb
+++ b/activesupport/test/json/encoding_test_cases.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "bigdecimal"
 require "date"
 require "time"
diff --git a/activesupport/test/key_generator_test.rb b/activesupport/test/key_generator_test.rb
index 89db9563ac..ae7018274a 100644
--- a/activesupport/test/key_generator_test.rb
+++ b/activesupport/test/key_generator_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 begin
diff --git a/activesupport/test/lazy_load_hooks_test.rb b/activesupport/test/lazy_load_hooks_test.rb
index 3b1959a1c9..761fe46094 100644
--- a/activesupport/test/lazy_load_hooks_test.rb
+++ b/activesupport/test/lazy_load_hooks_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class LazyLoadHooksTest < ActiveSupport::TestCase
diff --git a/activesupport/test/log_subscriber_test.rb b/activesupport/test/log_subscriber_test.rb
index f6496ef7d6..f30932452f 100644
--- a/activesupport/test/log_subscriber_test.rb
+++ b/activesupport/test/log_subscriber_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/log_subscriber/test_helper"
 
diff --git a/activesupport/test/logger_test.rb b/activesupport/test/logger_test.rb
index 1bc443ae65..cd0ddb4b97 100644
--- a/activesupport/test/logger_test.rb
+++ b/activesupport/test/logger_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "multibyte_test_helpers"
 require "stringio"
diff --git a/activesupport/test/message_encryptor_test.rb b/activesupport/test/message_encryptor_test.rb
index 4c3515b5e1..33ab7620da 100644
--- a/activesupport/test/message_encryptor_test.rb
+++ b/activesupport/test/message_encryptor_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "openssl"
 require "active_support/time"
diff --git a/activesupport/test/message_verifier_test.rb b/activesupport/test/message_verifier_test.rb
index d6109c761d..d2964aeb7e 100644
--- a/activesupport/test/message_verifier_test.rb
+++ b/activesupport/test/message_verifier_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "openssl"
 require "active_support/time"
diff --git a/activesupport/test/multibyte_chars_test.rb b/activesupport/test/multibyte_chars_test.rb
index 16a7d488c7..6bef794fe2 100644
--- a/activesupport/test/multibyte_chars_test.rb
+++ b/activesupport/test/multibyte_chars_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "multibyte_test_helpers"
 require "active_support/core_ext/string/multibyte"
diff --git a/activesupport/test/multibyte_conformance_test.rb b/activesupport/test/multibyte_conformance_test.rb
index ef1a26135f..be89c85c79 100644
--- a/activesupport/test/multibyte_conformance_test.rb
+++ b/activesupport/test/multibyte_conformance_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "multibyte_test_helpers"
 
diff --git a/activesupport/test/multibyte_grapheme_break_conformance_test.rb b/activesupport/test/multibyte_grapheme_break_conformance_test.rb
index b3328987ae..855626e779 100644
--- a/activesupport/test/multibyte_grapheme_break_conformance_test.rb
+++ b/activesupport/test/multibyte_grapheme_break_conformance_test.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: true
 
 require "abstract_unit"
 require "multibyte_test_helpers"
diff --git a/activesupport/test/multibyte_normalization_conformance_test.rb b/activesupport/test/multibyte_normalization_conformance_test.rb
index ebc9f92d23..deb94a7aa3 100644
--- a/activesupport/test/multibyte_normalization_conformance_test.rb
+++ b/activesupport/test/multibyte_normalization_conformance_test.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: true
 
 require "abstract_unit"
 require "multibyte_test_helpers"
diff --git a/activesupport/test/multibyte_proxy_test.rb b/activesupport/test/multibyte_proxy_test.rb
index c303097f80..27d5cea836 100644
--- a/activesupport/test/multibyte_proxy_test.rb
+++ b/activesupport/test/multibyte_proxy_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class MultibyteProxyText < ActiveSupport::TestCase
diff --git a/activesupport/test/multibyte_test_helpers.rb b/activesupport/test/multibyte_test_helpers.rb
index e1e0ae86d9..c3346c233a 100644
--- a/activesupport/test/multibyte_test_helpers.rb
+++ b/activesupport/test/multibyte_test_helpers.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module MultibyteTestHelpers
   class Downloader
     def self.download(from, to)
diff --git a/activesupport/test/multibyte_unicode_database_test.rb b/activesupport/test/multibyte_unicode_database_test.rb
index 3724782930..0defa6dc54 100644
--- a/activesupport/test/multibyte_unicode_database_test.rb
+++ b/activesupport/test/multibyte_unicode_database_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class MultibyteUnicodeDatabaseTest < ActiveSupport::TestCase
diff --git a/activesupport/test/notifications/evented_notification_test.rb b/activesupport/test/notifications/evented_notification_test.rb
index 24c5befec3..1fd50d540b 100644
--- a/activesupport/test/notifications/evented_notification_test.rb
+++ b/activesupport/test/notifications/evented_notification_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 module ActiveSupport
diff --git a/activesupport/test/notifications/instrumenter_test.rb b/activesupport/test/notifications/instrumenter_test.rb
index 7eacc5cbe7..122afa1cae 100644
--- a/activesupport/test/notifications/instrumenter_test.rb
+++ b/activesupport/test/notifications/instrumenter_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/notifications/instrumenter"
 
diff --git a/activesupport/test/notifications_test.rb b/activesupport/test/notifications_test.rb
index 11f743519f..d92c059f36 100644
--- a/activesupport/test/notifications_test.rb
+++ b/activesupport/test/notifications_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/module/delegation"
 
diff --git a/activesupport/test/number_helper_i18n_test.rb b/activesupport/test/number_helper_i18n_test.rb
index a1d1c41dc2..b5ac343390 100644
--- a/activesupport/test/number_helper_i18n_test.rb
+++ b/activesupport/test/number_helper_i18n_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/number_helper"
 require "active_support/core_ext/hash/keys"
diff --git a/activesupport/test/number_helper_test.rb b/activesupport/test/number_helper_test.rb
index 4caf1428ea..db99ba649f 100644
--- a/activesupport/test/number_helper_test.rb
+++ b/activesupport/test/number_helper_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/number_helper"
 require "active_support/core_ext/string/output_safety"
diff --git a/activesupport/test/option_merger_test.rb b/activesupport/test/option_merger_test.rb
index c5a6d304ee..90291d6ea8 100644
--- a/activesupport/test/option_merger_test.rb
+++ b/activesupport/test/option_merger_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/object/with_options"
 
diff --git a/activesupport/test/ordered_hash_test.rb b/activesupport/test/ordered_hash_test.rb
index 2cefab3832..5d7b83d7a2 100644
--- a/activesupport/test/ordered_hash_test.rb
+++ b/activesupport/test/ordered_hash_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/json"
 require "active_support/core_ext/object/json"
diff --git a/activesupport/test/ordered_options_test.rb b/activesupport/test/ordered_options_test.rb
index 0417911289..7ff8e01540 100644
--- a/activesupport/test/ordered_options_test.rb
+++ b/activesupport/test/ordered_options_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/ordered_options"
 
diff --git a/activesupport/test/reloader_test.rb b/activesupport/test/reloader_test.rb
index bdd80307c7..8dafbff04c 100644
--- a/activesupport/test/reloader_test.rb
+++ b/activesupport/test/reloader_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class ReloaderTest < ActiveSupport::TestCase
diff --git a/activesupport/test/rescuable_test.rb b/activesupport/test/rescuable_test.rb
index 3bdd1651e7..96ed3718af 100644
--- a/activesupport/test/rescuable_test.rb
+++ b/activesupport/test/rescuable_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class WraithAttack < StandardError
diff --git a/activesupport/test/safe_buffer_test.rb b/activesupport/test/safe_buffer_test.rb
index 36c068b91f..5a0f6539a4 100644
--- a/activesupport/test/safe_buffer_test.rb
+++ b/activesupport/test/safe_buffer_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/string/inflections"
 require "yaml"
diff --git a/activesupport/test/security_utils_test.rb b/activesupport/test/security_utils_test.rb
index e8f762da22..34f2eea919 100644
--- a/activesupport/test/security_utils_test.rb
+++ b/activesupport/test/security_utils_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/security_utils"
 
diff --git a/activesupport/test/share_lock_test.rb b/activesupport/test/share_lock_test.rb
index a5970591fa..7d850b4757 100644
--- a/activesupport/test/share_lock_test.rb
+++ b/activesupport/test/share_lock_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "concurrent/atomic/count_down_latch"
 require "active_support/concurrency/share_lock"
diff --git a/activesupport/test/string_inquirer_test.rb b/activesupport/test/string_inquirer_test.rb
index 79a715349c..ba9791886d 100644
--- a/activesupport/test/string_inquirer_test.rb
+++ b/activesupport/test/string_inquirer_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class StringInquirerTest < ActiveSupport::TestCase
diff --git a/activesupport/test/subscriber_test.rb b/activesupport/test/subscriber_test.rb
index 9127da35d4..33f89d237e 100644
--- a/activesupport/test/subscriber_test.rb
+++ b/activesupport/test/subscriber_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/subscriber"
 
diff --git a/activesupport/test/tagged_logging_test.rb b/activesupport/test/tagged_logging_test.rb
index 2469e827d4..e35ddba74b 100644
--- a/activesupport/test/tagged_logging_test.rb
+++ b/activesupport/test/tagged_logging_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/logger"
 require "active_support/tagged_logging"
diff --git a/activesupport/test/test_case_test.rb b/activesupport/test/test_case_test.rb
index 40dfbe2542..bc83fc3f07 100644
--- a/activesupport/test/test_case_test.rb
+++ b/activesupport/test/test_case_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 class AssertDifferenceTest < ActiveSupport::TestCase
diff --git a/activesupport/test/testing/constant_lookup_test.rb b/activesupport/test/testing/constant_lookup_test.rb
index 00e69fcdb5..02ef708a63 100644
--- a/activesupport/test/testing/constant_lookup_test.rb
+++ b/activesupport/test/testing/constant_lookup_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "dependencies_test_helpers"
 
diff --git a/activesupport/test/testing/file_fixtures_test.rb b/activesupport/test/testing/file_fixtures_test.rb
index 9f28252c31..cc00e7f113 100644
--- a/activesupport/test/testing/file_fixtures_test.rb
+++ b/activesupport/test/testing/file_fixtures_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 
 require "pathname"
diff --git a/activesupport/test/testing/method_call_assertions_test.rb b/activesupport/test/testing/method_call_assertions_test.rb
index 7887933b15..3912c19b80 100644
--- a/activesupport/test/testing/method_call_assertions_test.rb
+++ b/activesupport/test/testing/method_call_assertions_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/testing/method_call_assertions"
 
diff --git a/activesupport/test/time_travel_test.rb b/activesupport/test/time_travel_test.rb
index 9d354f14f4..616015b74e 100644
--- a/activesupport/test/time_travel_test.rb
+++ b/activesupport/test/time_travel_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/core_ext/date_time"
 require "active_support/core_ext/numeric/time"
diff --git a/activesupport/test/time_zone_test.rb b/activesupport/test/time_zone_test.rb
index de111cc40e..f1a1e44a8f 100644
--- a/activesupport/test/time_zone_test.rb
+++ b/activesupport/test/time_zone_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/time"
 require "time_zone_test_helpers"
diff --git a/activesupport/test/time_zone_test_helpers.rb b/activesupport/test/time_zone_test_helpers.rb
index e1d615d154..118dc38b5c 100644
--- a/activesupport/test/time_zone_test_helpers.rb
+++ b/activesupport/test/time_zone_test_helpers.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module TimeZoneTestHelpers
   def with_tz_default(tz = nil)
     old_tz = Time.zone
diff --git a/activesupport/test/transliterate_test.rb b/activesupport/test/transliterate_test.rb
index 466b69bcef..1359fe8a8d 100644
--- a/activesupport/test/transliterate_test.rb
+++ b/activesupport/test/transliterate_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/inflector/transliterate"
 
diff --git a/activesupport/test/xml_mini/jdom_engine_test.rb b/activesupport/test/xml_mini/jdom_engine_test.rb
index fc35ac113b..ae78a0e547 100644
--- a/activesupport/test/xml_mini/jdom_engine_test.rb
+++ b/activesupport/test/xml_mini/jdom_engine_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "xml_mini_engine_test"
 
 XMLMiniEngineTest.run_with_platform("java") do
diff --git a/activesupport/test/xml_mini/libxml_engine_test.rb b/activesupport/test/xml_mini/libxml_engine_test.rb
index f3394ad7f2..64ef5b61a1 100644
--- a/activesupport/test/xml_mini/libxml_engine_test.rb
+++ b/activesupport/test/xml_mini/libxml_engine_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "xml_mini_engine_test"
 
 XMLMiniEngineTest.run_with_gem("libxml") do
diff --git a/activesupport/test/xml_mini/libxmlsax_engine_test.rb b/activesupport/test/xml_mini/libxmlsax_engine_test.rb
index f457e160d6..deeb01eefe 100644
--- a/activesupport/test/xml_mini/libxmlsax_engine_test.rb
+++ b/activesupport/test/xml_mini/libxmlsax_engine_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "xml_mini_engine_test"
 
 XMLMiniEngineTest.run_with_gem("libxml") do
diff --git a/activesupport/test/xml_mini/nokogiri_engine_test.rb b/activesupport/test/xml_mini/nokogiri_engine_test.rb
index 3151e75fc0..10062577f6 100644
--- a/activesupport/test/xml_mini/nokogiri_engine_test.rb
+++ b/activesupport/test/xml_mini/nokogiri_engine_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "xml_mini_engine_test"
 
 XMLMiniEngineTest.run_with_gem("nokogiri") do
diff --git a/activesupport/test/xml_mini/nokogirisax_engine_test.rb b/activesupport/test/xml_mini/nokogirisax_engine_test.rb
index 7dafbdaf48..9d298b77d3 100644
--- a/activesupport/test/xml_mini/nokogirisax_engine_test.rb
+++ b/activesupport/test/xml_mini/nokogirisax_engine_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "xml_mini_engine_test"
 
 XMLMiniEngineTest.run_with_gem("nokogiri") do
diff --git a/activesupport/test/xml_mini/rexml_engine_test.rb b/activesupport/test/xml_mini/rexml_engine_test.rb
index c51f0d3c20..29a9dbfbeb 100644
--- a/activesupport/test/xml_mini/rexml_engine_test.rb
+++ b/activesupport/test/xml_mini/rexml_engine_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require_relative "xml_mini_engine_test"
 
 class REXMLEngineTest < XMLMiniEngineTest
diff --git a/activesupport/test/xml_mini/xml_mini_engine_test.rb b/activesupport/test/xml_mini/xml_mini_engine_test.rb
index 244e0b0d3a..6e6be2ff0a 100644
--- a/activesupport/test/xml_mini/xml_mini_engine_test.rb
+++ b/activesupport/test/xml_mini/xml_mini_engine_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/xml_mini"
 require "active_support/core_ext/hash/conversions"
diff --git a/activesupport/test/xml_mini_test.rb b/activesupport/test/xml_mini_test.rb
index b8caa1d74c..cf66e9ff41 100644
--- a/activesupport/test/xml_mini_test.rb
+++ b/activesupport/test/xml_mini_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "abstract_unit"
 require "active_support/xml_mini"
 require "active_support/builder"