diff --git a/actionmailer/test/abstract_unit.rb b/actionmailer/test/abstract_unit.rb
index 99c44179fd..15729bafba 100644
--- a/actionmailer/test/abstract_unit.rb
+++ b/actionmailer/test/abstract_unit.rb
@@ -8,7 +8,7 @@ silence_warnings do
   Encoding.default_external = "UTF-8"
 end
 
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
 require 'action_mailer'
 require 'action_mailer/test_case'
 
diff --git a/actionpack/test/abstract_unit.rb b/actionpack/test/abstract_unit.rb
index 95bff0a204..bbcd289886 100644
--- a/actionpack/test/abstract_unit.rb
+++ b/actionpack/test/abstract_unit.rb
@@ -15,7 +15,7 @@ silence_warnings do
   Encoding.default_external = "UTF-8"
 end
 
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
 require 'abstract_controller'
 require 'action_controller'
 require 'action_view'
diff --git a/actionpack/test/dispatch/routing/inspector_test.rb b/actionpack/test/dispatch/routing/inspector_test.rb
index a3034ce001..c058bd4909 100644
--- a/actionpack/test/dispatch/routing/inspector_test.rb
+++ b/actionpack/test/dispatch/routing/inspector_test.rb
@@ -1,4 +1,4 @@
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
 require 'action_controller'
 require 'rails/engine'
 require 'action_dispatch/routing/inspector'
diff --git a/actionpack/test/ts_isolated.rb b/actionpack/test/ts_isolated.rb
index c44c5d8968..55620abe84 100644
--- a/actionpack/test/ts_isolated.rb
+++ b/actionpack/test/ts_isolated.rb
@@ -1,4 +1,4 @@
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
 require 'rbconfig'
 require 'abstract_unit'
 
diff --git a/activemodel/test/cases/helper.rb b/activemodel/test/cases/helper.rb
index 7d6f11b5a5..7a63674757 100644
--- a/activemodel/test/cases/helper.rb
+++ b/activemodel/test/cases/helper.rb
@@ -7,4 +7,4 @@ require 'active_support/core_ext/string/access'
 # Show backtraces for deprecated behavior for quicker cleanup.
 ActiveSupport::Deprecation.debug = true
 
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
diff --git a/activerecord/test/cases/helper.rb b/activerecord/test/cases/helper.rb
index 3a315d843b..5ffb32e809 100644
--- a/activerecord/test/cases/helper.rb
+++ b/activerecord/test/cases/helper.rb
@@ -2,8 +2,7 @@ require File.expand_path('../../../../load_paths', __FILE__)
 
 require 'config'
 
-gem 'minitest'
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
 require 'stringio'
 
 require 'active_record'
diff --git a/activerecord/test/cases/migration/change_table_test.rb b/activerecord/test/cases/migration/change_table_test.rb
index ac1ad176db..8065541bfe 100644
--- a/activerecord/test/cases/migration/change_table_test.rb
+++ b/activerecord/test/cases/migration/change_table_test.rb
@@ -1,4 +1,5 @@
 require "cases/migration/helper"
+require "minitest/mock"
 
 module ActiveRecord
   class Migration
diff --git a/activesupport/lib/active_support/testing/autorun.rb b/activesupport/lib/active_support/testing/autorun.rb
new file mode 100644
index 0000000000..c446adc16d
--- /dev/null
+++ b/activesupport/lib/active_support/testing/autorun.rb
@@ -0,0 +1,5 @@
+gem 'minitest'
+
+require 'minitest/unit'
+
+MiniTest::Unit.autorun
diff --git a/activesupport/test/abstract_unit.rb b/activesupport/test/abstract_unit.rb
index 8a67b148c3..90e50f235b 100644
--- a/activesupport/test/abstract_unit.rb
+++ b/activesupport/test/abstract_unit.rb
@@ -15,7 +15,7 @@ silence_warnings do
   Encoding.default_external = "UTF-8"
 end
 
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
 require 'empty_bool'
 
 ENV['NO_RELOAD'] = '1'
diff --git a/activesupport/test/ts_isolated.rb b/activesupport/test/ts_isolated.rb
index 2c217157d3..294d6595f7 100644
--- a/activesupport/test/ts_isolated.rb
+++ b/activesupport/test/ts_isolated.rb
@@ -1,4 +1,4 @@
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
 require 'active_support/test_case'
 require 'rbconfig'
 require 'active_support/core_ext/kernel/reporting'
diff --git a/railties/lib/rails/generators/test_unit/plugin/templates/test_helper.rb b/railties/lib/rails/generators/test_unit/plugin/templates/test_helper.rb
index c9af2ca832..30a861f09d 100644
--- a/railties/lib/rails/generators/test_unit/plugin/templates/test_helper.rb
+++ b/railties/lib/rails/generators/test_unit/plugin/templates/test_helper.rb
@@ -1,2 +1,2 @@
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
 require 'active_support'
diff --git a/railties/lib/rails/test_help.rb b/railties/lib/rails/test_help.rb
index aed7fd4b14..616206dd0b 100644
--- a/railties/lib/rails/test_help.rb
+++ b/railties/lib/rails/test_help.rb
@@ -2,7 +2,7 @@
 # so fixtures aren't loaded into that environment
 abort("Abort testing: Your Rails environment is running in production mode!") if Rails.env.production?
 
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
 require 'active_support/test_case'
 require 'action_controller/test_case'
 require 'action_dispatch/testing/integration'
diff --git a/railties/test/abstract_unit.rb b/railties/test/abstract_unit.rb
index ecd5e03978..491faf4af9 100644
--- a/railties/test/abstract_unit.rb
+++ b/railties/test/abstract_unit.rb
@@ -3,7 +3,7 @@ ENV["RAILS_ENV"] ||= "test"
 require File.expand_path("../../../load_paths", __FILE__)
 
 require 'stringio'
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
 require 'fileutils'
 
 require 'active_support'
diff --git a/railties/test/configuration/middleware_stack_proxy_test.rb b/railties/test/configuration/middleware_stack_proxy_test.rb
index 5984c0b425..2442cb995d 100644
--- a/railties/test/configuration/middleware_stack_proxy_test.rb
+++ b/railties/test/configuration/middleware_stack_proxy_test.rb
@@ -1,6 +1,7 @@
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
 require 'rails/configuration'
 require 'active_support/test_case'
+require 'minitest/mock'
 
 module Rails
   module Configuration
diff --git a/railties/test/isolation/abstract_unit.rb b/railties/test/isolation/abstract_unit.rb
index 0cb65f8e0d..172a42a549 100644
--- a/railties/test/isolation/abstract_unit.rb
+++ b/railties/test/isolation/abstract_unit.rb
@@ -9,7 +9,7 @@
 require 'fileutils'
 
 require 'bundler/setup' unless defined?(Bundler)
-require 'minitest/autorun'
+require 'active_support/testing/autorun'
 require 'active_support/test_case'
 
 RAILS_FRAMEWORK_ROOT = File.expand_path("#{File.dirname(__FILE__)}/../../..")