diff --git a/actionmailer/test/base_test.rb b/actionmailer/test/base_test.rb
index b218d923e5..59c5638f96 100644
--- a/actionmailer/test/base_test.rb
+++ b/actionmailer/test/base_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'set'
 
diff --git a/actionmailer/test/message_delivery_test.rb b/actionmailer/test/message_delivery_test.rb
index 55ee00602a..e4dd269494 100644
--- a/actionmailer/test/message_delivery_test.rb
+++ b/actionmailer/test/message_delivery_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'active_job'
 require 'minitest/mock'
diff --git a/actionmailer/test/test_helper_test.rb b/actionmailer/test/test_helper_test.rb
index 21e7154c43..772751af87 100644
--- a/actionmailer/test/test_helper_test.rb
+++ b/actionmailer/test/test_helper_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 
 class TestHelperMailer < ActionMailer::Base
diff --git a/actionpack/test/controller/routing_test.rb b/actionpack/test/controller/routing_test.rb
index 9caa5cbe57..2d08987ca6 100644
--- a/actionpack/test/controller/routing_test.rb
+++ b/actionpack/test/controller/routing_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'controller/fake_controllers'
 require 'active_support/core_ext/object/with_options'
diff --git a/actionpack/test/controller/send_file_test.rb b/actionpack/test/controller/send_file_test.rb
index c002cf4d8f..36c57ec9b2 100644
--- a/actionpack/test/controller/send_file_test.rb
+++ b/actionpack/test/controller/send_file_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 
 module TestFileUtils
diff --git a/actionpack/test/controller/url_for_integration_test.rb b/actionpack/test/controller/url_for_integration_test.rb
index 24a09222b1..0e4c2b7c32 100644
--- a/actionpack/test/controller/url_for_integration_test.rb
+++ b/actionpack/test/controller/url_for_integration_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'controller/fake_controllers'
 require 'active_support/core_ext/object/with_options'
diff --git a/actionpack/test/dispatch/request/multipart_params_parsing_test.rb b/actionpack/test/dispatch/request/multipart_params_parsing_test.rb
index 6d1b267ad2..50f69c53cb 100644
--- a/actionpack/test/dispatch/request/multipart_params_parsing_test.rb
+++ b/actionpack/test/dispatch/request/multipart_params_parsing_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 
 class MultipartParamsParsingTest < ActionDispatch::IntegrationTest
diff --git a/actionpack/test/dispatch/static_test.rb b/actionpack/test/dispatch/static_test.rb
index 9a6747fb8d..ebc9d71403 100644
--- a/actionpack/test/dispatch/static_test.rb
+++ b/actionpack/test/dispatch/static_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'zlib'
 
diff --git a/actionpack/test/journey/router/utils_test.rb b/actionpack/test/journey/router/utils_test.rb
index 9b2b85ec73..2b505f081e 100644
--- a/actionpack/test/journey/router/utils_test.rb
+++ b/actionpack/test/journey/router/utils_test.rb
@@ -1,4 +1,3 @@
-# coding: utf-8
 require 'abstract_unit'
 
 module ActionDispatch
diff --git a/actionview/lib/action_view/helpers/number_helper.rb b/actionview/lib/action_view/helpers/number_helper.rb
index f66dbfe7d3..cfd617cedc 100644
--- a/actionview/lib/action_view/helpers/number_helper.rb
+++ b/actionview/lib/action_view/helpers/number_helper.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 
 require 'active_support/core_ext/hash/keys'
 require 'active_support/core_ext/string/output_safety'
diff --git a/actionview/test/template/dependency_tracker_test.rb b/actionview/test/template/dependency_tracker_test.rb
index bb375076c6..d74da4c318 100644
--- a/actionview/test/template/dependency_tracker_test.rb
+++ b/actionview/test/template/dependency_tracker_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 
 require 'abstract_unit'
 require 'action_view/dependency_tracker'
diff --git a/actionview/test/template/render_test.rb b/actionview/test/template/render_test.rb
index dc4abca048..66667e0474 100644
--- a/actionview/test/template/render_test.rb
+++ b/actionview/test/template/render_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'controller/fake_models'
 
diff --git a/actionview/test/template/streaming_render_test.rb b/actionview/test/template/streaming_render_test.rb
index 8a24d78e74..ec537775be 100644
--- a/actionview/test/template/streaming_render_test.rb
+++ b/actionview/test/template/streaming_render_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 
 class TestController < ActionController::Base
diff --git a/actionview/test/template/text_helper_test.rb b/actionview/test/template/text_helper_test.rb
index f05b845e46..f1b84c4786 100644
--- a/actionview/test/template/text_helper_test.rb
+++ b/actionview/test/template/text_helper_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 
 class TextHelperTest < ActionView::TestCase
diff --git a/actionview/test/template/url_helper_test.rb b/actionview/test/template/url_helper_test.rb
index 0ce9d38fa3..ee3313489f 100644
--- a/actionview/test/template/url_helper_test.rb
+++ b/actionview/test/template/url_helper_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'minitest/mock'
 
diff --git a/activemodel/test/cases/validations/absence_validation_test.rb b/activemodel/test/cases/validations/absence_validation_test.rb
index ebfe1cf4e4..9cbc77dfb5 100644
--- a/activemodel/test/cases/validations/absence_validation_test.rb
+++ b/activemodel/test/cases/validations/absence_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 require 'models/topic'
 require 'models/person'
diff --git a/activemodel/test/cases/validations/acceptance_validation_test.rb b/activemodel/test/cases/validations/acceptance_validation_test.rb
index b7872ea6bf..9c2114d83d 100644
--- a/activemodel/test/cases/validations/acceptance_validation_test.rb
+++ b/activemodel/test/cases/validations/acceptance_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/callbacks_test.rb b/activemodel/test/cases/validations/callbacks_test.rb
index cc50ffbbef..75eb18e795 100644
--- a/activemodel/test/cases/validations/callbacks_test.rb
+++ b/activemodel/test/cases/validations/callbacks_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 class Dog
diff --git a/activemodel/test/cases/validations/conditional_validation_test.rb b/activemodel/test/cases/validations/conditional_validation_test.rb
index 1261937b56..296d3b4407 100644
--- a/activemodel/test/cases/validations/conditional_validation_test.rb
+++ b/activemodel/test/cases/validations/conditional_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/confirmation_validation_test.rb b/activemodel/test/cases/validations/confirmation_validation_test.rb
index 65a2a1eb49..c1431548f7 100644
--- a/activemodel/test/cases/validations/confirmation_validation_test.rb
+++ b/activemodel/test/cases/validations/confirmation_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/exclusion_validation_test.rb b/activemodel/test/cases/validations/exclusion_validation_test.rb
index 1ce41f9bc9..b269c3691a 100644
--- a/activemodel/test/cases/validations/exclusion_validation_test.rb
+++ b/activemodel/test/cases/validations/exclusion_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/format_validation_test.rb b/activemodel/test/cases/validations/format_validation_test.rb
index 0f91b73cd7..86bbbe6ebe 100644
--- a/activemodel/test/cases/validations/format_validation_test.rb
+++ b/activemodel/test/cases/validations/format_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/i18n_validation_test.rb b/activemodel/test/cases/validations/i18n_validation_test.rb
index 96084a32ba..70ee7afecc 100644
--- a/activemodel/test/cases/validations/i18n_validation_test.rb
+++ b/activemodel/test/cases/validations/i18n_validation_test.rb
@@ -1,5 +1,3 @@
-# -*- coding: utf-8 -*-
-
 require "cases/helper"
 require 'models/person'
 
diff --git a/activemodel/test/cases/validations/inclusion_validation_test.rb b/activemodel/test/cases/validations/inclusion_validation_test.rb
index 3a8f3080e1..55d1fb4dcb 100644
--- a/activemodel/test/cases/validations/inclusion_validation_test.rb
+++ b/activemodel/test/cases/validations/inclusion_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 require 'active_support/all'
 
diff --git a/activemodel/test/cases/validations/length_validation_test.rb b/activemodel/test/cases/validations/length_validation_test.rb
index 046ffcb16f..29130ce46c 100644
--- a/activemodel/test/cases/validations/length_validation_test.rb
+++ b/activemodel/test/cases/validations/length_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/numericality_validation_test.rb b/activemodel/test/cases/validations/numericality_validation_test.rb
index 12a22f9c40..05432abaff 100644
--- a/activemodel/test/cases/validations/numericality_validation_test.rb
+++ b/activemodel/test/cases/validations/numericality_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/presence_validation_test.rb b/activemodel/test/cases/validations/presence_validation_test.rb
index ecf16d1e16..59b9db0795 100644
--- a/activemodel/test/cases/validations/presence_validation_test.rb
+++ b/activemodel/test/cases/validations/presence_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/validates_test.rb b/activemodel/test/cases/validations/validates_test.rb
index 8d4b74ee49..04101f3545 100644
--- a/activemodel/test/cases/validations/validates_test.rb
+++ b/activemodel/test/cases/validations/validates_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 require 'models/person'
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/validations_context_test.rb b/activemodel/test/cases/validations/validations_context_test.rb
index 005bf118c6..150dce379f 100644
--- a/activemodel/test/cases/validations/validations_context_test.rb
+++ b/activemodel/test/cases/validations/validations_context_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations/with_validation_test.rb b/activemodel/test/cases/validations/with_validation_test.rb
index 736c2deea8..01804032f0 100644
--- a/activemodel/test/cases/validations/with_validation_test.rb
+++ b/activemodel/test/cases/validations/with_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activemodel/test/cases/validations_test.rb b/activemodel/test/cases/validations_test.rb
index 2b932683ea..dc125bc884 100644
--- a/activemodel/test/cases/validations_test.rb
+++ b/activemodel/test/cases/validations_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 
 require 'models/topic'
diff --git a/activerecord/test/cases/adapters/mysql/mysql_adapter_test.rb b/activerecord/test/cases/adapters/mysql/mysql_adapter_test.rb
index 1e6511620a..7d0bd24ba7 100644
--- a/activerecord/test/cases/adapters/mysql/mysql_adapter_test.rb
+++ b/activerecord/test/cases/adapters/mysql/mysql_adapter_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 
 require "cases/helper"
 require 'support/ddl_helper'
diff --git a/activerecord/test/cases/adapters/postgresql/array_test.rb b/activerecord/test/cases/adapters/postgresql/array_test.rb
index b908b9b394..35b792b1c2 100644
--- a/activerecord/test/cases/adapters/postgresql/array_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/array_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
diff --git a/activerecord/test/cases/adapters/postgresql/bit_string_test.rb b/activerecord/test/cases/adapters/postgresql/bit_string_test.rb
index ad433b9d1b..d6b976a6d0 100644
--- a/activerecord/test/cases/adapters/postgresql/bit_string_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/bit_string_test.rb
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 require "cases/helper"
 require 'support/connection_helper'
 require 'support/schema_dumping_helper'
diff --git a/activerecord/test/cases/adapters/postgresql/bytea_test.rb b/activerecord/test/cases/adapters/postgresql/bytea_test.rb
index 99a7e88178..678a476661 100644
--- a/activerecord/test/cases/adapters/postgresql/bytea_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/bytea_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 
 class PostgresqlByteaTest < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/adapters/postgresql/citext_test.rb b/activerecord/test/cases/adapters/postgresql/citext_test.rb
index d7e611ac46..077f0271e2 100644
--- a/activerecord/test/cases/adapters/postgresql/citext_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/citext_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 require 'support/schema_dumping_helper'
 
diff --git a/activerecord/test/cases/adapters/postgresql/composite_test.rb b/activerecord/test/cases/adapters/postgresql/composite_test.rb
index be0025218e..0c0d2465b2 100644
--- a/activerecord/test/cases/adapters/postgresql/composite_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/composite_test.rb
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 require "cases/helper"
 require 'support/connection_helper'
 
diff --git a/activerecord/test/cases/adapters/postgresql/domain_test.rb b/activerecord/test/cases/adapters/postgresql/domain_test.rb
index d0d70122e9..702de07597 100644
--- a/activerecord/test/cases/adapters/postgresql/domain_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/domain_test.rb
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 require "cases/helper"
 require 'support/connection_helper'
 
diff --git a/activerecord/test/cases/adapters/postgresql/enum_test.rb b/activerecord/test/cases/adapters/postgresql/enum_test.rb
index dab3f92ab2..7739d2ee3b 100644
--- a/activerecord/test/cases/adapters/postgresql/enum_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/enum_test.rb
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 require "cases/helper"
 require 'support/connection_helper'
 
diff --git a/activerecord/test/cases/adapters/postgresql/full_text_test.rb b/activerecord/test/cases/adapters/postgresql/full_text_test.rb
index a38291cb0a..8357dcb3dc 100644
--- a/activerecord/test/cases/adapters/postgresql/full_text_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/full_text_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
diff --git a/activerecord/test/cases/adapters/postgresql/geometric_test.rb b/activerecord/test/cases/adapters/postgresql/geometric_test.rb
index 39b8daaa83..5d2e86c5a0 100644
--- a/activerecord/test/cases/adapters/postgresql/geometric_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/geometric_test.rb
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 require "cases/helper"
 require 'support/connection_helper'
 require 'support/schema_dumping_helper'
diff --git a/activerecord/test/cases/adapters/postgresql/hstore_test.rb b/activerecord/test/cases/adapters/postgresql/hstore_test.rb
index 7ed15b2be0..121f347986 100644
--- a/activerecord/test/cases/adapters/postgresql/hstore_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/hstore_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
diff --git a/activerecord/test/cases/adapters/postgresql/json_test.rb b/activerecord/test/cases/adapters/postgresql/json_test.rb
index ba72a1fdcb..dd7b67bad7 100644
--- a/activerecord/test/cases/adapters/postgresql/json_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/json_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
diff --git a/activerecord/test/cases/adapters/postgresql/ltree_test.rb b/activerecord/test/cases/adapters/postgresql/ltree_test.rb
index cdc3269408..ca17edfd03 100644
--- a/activerecord/test/cases/adapters/postgresql/ltree_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/ltree_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
diff --git a/activerecord/test/cases/adapters/postgresql/money_test.rb b/activerecord/test/cases/adapters/postgresql/money_test.rb
index ed1b7d0a1c..4288f754c0 100644
--- a/activerecord/test/cases/adapters/postgresql/money_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/money_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
diff --git a/activerecord/test/cases/adapters/postgresql/network_test.rb b/activerecord/test/cases/adapters/postgresql/network_test.rb
index cb75faa1e5..efe754ac7c 100644
--- a/activerecord/test/cases/adapters/postgresql/network_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/network_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
diff --git a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
index 15c2f48ede..564712522d 100644
--- a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/ddl_helper'
 require 'support/connection_helper'
diff --git a/activerecord/test/cases/adapters/postgresql/uuid_test.rb b/activerecord/test/cases/adapters/postgresql/uuid_test.rb
index ad86d617b8..1d0f013a26 100644
--- a/activerecord/test/cases/adapters/postgresql/uuid_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/uuid_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'support/schema_dumping_helper'
 
diff --git a/activerecord/test/cases/adapters/postgresql/xml_test.rb b/activerecord/test/cases/adapters/postgresql/xml_test.rb
index ac8464a65d..05b34dcf7d 100644
--- a/activerecord/test/cases/adapters/postgresql/xml_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/xml_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'cases/helper'
 require 'support/schema_dumping_helper'
 
diff --git a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
index 0527bf8b15..f916d99bcf 100644
--- a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'models/owner'
 require 'tempfile'
diff --git a/activerecord/test/cases/adapters/sqlite3/sqlite3_create_folder_test.rb b/activerecord/test/cases/adapters/sqlite3/sqlite3_create_folder_test.rb
index f545fc2011..deedf67c8e 100644
--- a/activerecord/test/cases/adapters/sqlite3/sqlite3_create_folder_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/sqlite3_create_folder_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'models/owner'
 
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 0debd30e5c..7c5939fc47 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 
 require "cases/helper"
 require 'active_support/concurrency/latch'
diff --git a/activerecord/test/cases/binary_test.rb b/activerecord/test/cases/binary_test.rb
index ccf2be369d..86dee929bf 100644
--- a/activerecord/test/cases/binary_test.rb
+++ b/activerecord/test/cases/binary_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 
 # Without using prepared statements, it makes no sense to test
diff --git a/activerecord/test/cases/integration_test.rb b/activerecord/test/cases/integration_test.rb
index 0021988083..018b7b0d8f 100644
--- a/activerecord/test/cases/integration_test.rb
+++ b/activerecord/test/cases/integration_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 
 require 'cases/helper'
 require 'models/company'
diff --git a/activerecord/test/cases/validations/length_validation_test.rb b/activerecord/test/cases/validations/length_validation_test.rb
index 8b69a6815e..952e1681a7 100644
--- a/activerecord/test/cases/validations/length_validation_test.rb
+++ b/activerecord/test/cases/validations/length_validation_test.rb
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 require "cases/helper"
 require 'models/owner'
 require 'models/pet'
diff --git a/activerecord/test/cases/validations/presence_validation_test.rb b/activerecord/test/cases/validations/presence_validation_test.rb
index b5b16d7a9b..6f8ad06ab6 100644
--- a/activerecord/test/cases/validations/presence_validation_test.rb
+++ b/activerecord/test/cases/validations/presence_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'models/man'
 require 'models/face'
diff --git a/activerecord/test/cases/validations/uniqueness_validation_test.rb b/activerecord/test/cases/validations/uniqueness_validation_test.rb
index d41b26a2e5..062bc733f9 100644
--- a/activerecord/test/cases/validations/uniqueness_validation_test.rb
+++ b/activerecord/test/cases/validations/uniqueness_validation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'models/topic'
 require 'models/reply'
diff --git a/activerecord/test/cases/validations_test.rb b/activerecord/test/cases/validations_test.rb
index 959c58aa85..b0f34e5f47 100644
--- a/activerecord/test/cases/validations_test.rb
+++ b/activerecord/test/cases/validations_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require "cases/helper"
 require 'models/topic'
 require 'models/reply'
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index 49dbc5dabf..a7d90e3f89 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 
 ActiveRecord::Schema.define do
   def except(adapter_names_to_exclude)
diff --git a/activesupport/lib/active_support/core_ext/string/multibyte.rb b/activesupport/lib/active_support/core_ext/string/multibyte.rb
index a124202936..2eedd4fdb1 100644
--- a/activesupport/lib/active_support/core_ext/string/multibyte.rb
+++ b/activesupport/lib/active_support/core_ext/string/multibyte.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'active_support/multibyte'
 
 class String
diff --git a/activesupport/test/core_ext/object/blank_test.rb b/activesupport/test/core_ext/object/blank_test.rb
index 246bc7fa61..8a5e385dd7 100644
--- a/activesupport/test/core_ext/object/blank_test.rb
+++ b/activesupport/test/core_ext/object/blank_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 
 require 'abstract_unit'
 require 'active_support/core_ext/object/blank'
diff --git a/activesupport/test/core_ext/string_ext_test.rb b/activesupport/test/core_ext/string_ext_test.rb
index cdc695f036..24037c665a 100644
--- a/activesupport/test/core_ext/string_ext_test.rb
+++ b/activesupport/test/core_ext/string_ext_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'date'
 require 'abstract_unit'
 require 'inflector_test_cases'
diff --git a/activesupport/test/core_ext/uri_ext_test.rb b/activesupport/test/core_ext/uri_ext_test.rb
index 43a5997ddd..1694fe7e72 100644
--- a/activesupport/test/core_ext/uri_ext_test.rb
+++ b/activesupport/test/core_ext/uri_ext_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'uri'
 require 'active_support/core_ext/uri'
diff --git a/activesupport/test/inflector_test_cases.rb b/activesupport/test/inflector_test_cases.rb
index 3770f00fe3..18a8b92eb9 100644
--- a/activesupport/test/inflector_test_cases.rb
+++ b/activesupport/test/inflector_test_cases.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 
 module InflectorTestCases
   SingularToPlural = {
diff --git a/activesupport/test/json/decoding_test.rb b/activesupport/test/json/decoding_test.rb
index 80bf255080..f2fc456f4b 100644
--- a/activesupport/test/json/decoding_test.rb
+++ b/activesupport/test/json/decoding_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 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 5c5045da1e..63d921e3b4 100644
--- a/activesupport/test/json/encoding_test.rb
+++ b/activesupport/test/json/encoding_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'securerandom'
 require 'abstract_unit'
 require 'active_support/core_ext/string/inflections'
diff --git a/activesupport/test/multibyte_chars_test.rb b/activesupport/test/multibyte_chars_test.rb
index 94748dd991..e1c4b705f8 100644
--- a/activesupport/test/multibyte_chars_test.rb
+++ b/activesupport/test/multibyte_chars_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 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 f7bd21c8ab..d8704716e7 100644
--- a/activesupport/test/multibyte_conformance_test.rb
+++ b/activesupport/test/multibyte_conformance_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 
 require 'abstract_unit'
 require 'multibyte_test_helpers'
diff --git a/activesupport/test/multibyte_proxy_test.rb b/activesupport/test/multibyte_proxy_test.rb
index d8ffd7ca9c..11f5374017 100644
--- a/activesupport/test/multibyte_proxy_test.rb
+++ b/activesupport/test/multibyte_proxy_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 
 require 'abstract_unit'
 
diff --git a/activesupport/test/multibyte_test_helpers.rb b/activesupport/test/multibyte_test_helpers.rb
index 90af2dadd4..2e4b5cc873 100644
--- a/activesupport/test/multibyte_test_helpers.rb
+++ b/activesupport/test/multibyte_test_helpers.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 
 module MultibyteTestHelpers
   UNICODE_STRING = 'こにちわ'.freeze
diff --git a/activesupport/test/multibyte_unicode_database_test.rb b/activesupport/test/multibyte_unicode_database_test.rb
index bec65daf50..52ae266f01 100644
--- a/activesupport/test/multibyte_unicode_database_test.rb
+++ b/activesupport/test/multibyte_unicode_database_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 
 
diff --git a/activesupport/test/transliterate_test.rb b/activesupport/test/transliterate_test.rb
index 6833ae68a7..378421fedd 100644
--- a/activesupport/test/transliterate_test.rb
+++ b/activesupport/test/transliterate_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'active_support/inflector/transliterate'
 
diff --git a/railties/test/application/assets_test.rb b/railties/test/application/assets_test.rb
index d58a27403e..0a2f283cce 100644
--- a/railties/test/application/assets_test.rb
+++ b/railties/test/application/assets_test.rb
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 require 'isolation/abstract_unit'
 require 'rack/test'
 require 'active_support/json'
diff --git a/railties/test/application/middleware/exceptions_test.rb b/railties/test/application/middleware/exceptions_test.rb
index a7472b37f1..4906f9a1e8 100644
--- a/railties/test/application/middleware/exceptions_test.rb
+++ b/railties/test/application/middleware/exceptions_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'isolation/abstract_unit'
 require 'rack/test'
 
diff --git a/railties/test/application/middleware/session_test.rb b/railties/test/application/middleware/session_test.rb
index eb7885e5b1..a8dc79d10a 100644
--- a/railties/test/application/middleware/session_test.rb
+++ b/railties/test/application/middleware/session_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'isolation/abstract_unit'
 require 'rack/test'
 
diff --git a/railties/test/application/middleware/static_test.rb b/railties/test/application/middleware/static_test.rb
index 0a793f8f60..121c5d3321 100644
--- a/railties/test/application/middleware/static_test.rb
+++ b/railties/test/application/middleware/static_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'isolation/abstract_unit'
 require 'rack/test'
 
diff --git a/railties/test/path_generation_test.rb b/railties/test/path_generation_test.rb
index 13bf29d3c3..e3dfcdfb7d 100644
--- a/railties/test/path_generation_test.rb
+++ b/railties/test/path_generation_test.rb
@@ -1,4 +1,3 @@
-# encoding: utf-8
 require 'abstract_unit'
 require 'active_support/core_ext/object/with_options'
 require 'active_support/core_ext/object/json'