Add `Style/RedundantFreeze` to remove redudant `.freeze`

Since Rails 6.0 will support Ruby 2.4.1 or higher
`# frozen_string_literal: true` magic comment is enough to make string object frozen.
This magic comment is enabled by `Style/FrozenStringLiteralComment` cop.

* Exclude these files not to auto correct false positive `Regexp#freeze`
 - 'actionpack/lib/action_dispatch/journey/router/utils.rb'
 - 'activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb'

It has been fixed by https://github.com/rubocop-hq/rubocop/pull/6333
Once the newer version of RuboCop released and available at Code Climate these exclude entries should be removed.

* Replace `String#freeze` with `String#-@` manually if explicit frozen string objects are required

 - 'actionpack/test/controller/test_case_test.rb'
 - 'activemodel/test/cases/type/string_test.rb'
 - 'activesupport/lib/active_support/core_ext/string/strip.rb'
 - 'activesupport/test/core_ext/string_ext_test.rb'
 - 'railties/test/generators/actions_test.rb'

3 files changed, 4 insertions, 4 deletions

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 266829a452..58a24b60b6 100644
--- a/activesupport/test/core_ext/date_and_time_compatibility_test.rb
+++ b/activesupport/test/core_ext/date_and_time_compatibility_test.rb
@@ -248,7 +248,7 @@ class DateAndTimeCompatibilityTest < ActiveSupport::TestCase
   def test_string_to_time_frozen_preserves_timezone
     with_preserve_timezone(true) do
       with_env_tz "US/Eastern" do
-        source = "2016-04-23T15:11:12+01:00".freeze
+        source = "2016-04-23T15:11:12+01:00"
         time = source.to_time
 
         assert_instance_of Time, time
@@ -262,7 +262,7 @@ class DateAndTimeCompatibilityTest < ActiveSupport::TestCase
   def test_string_to_time_frozen_does_not_preserve_time_zone
     with_preserve_timezone(false) do
       with_env_tz "US/Eastern" do
-        source = "2016-04-23T15:11:12+01:00".freeze
+        source = "2016-04-23T15:11:12+01:00"
         time = source.to_time
 
         assert_instance_of Time, time
diff --git a/activesupport/test/core_ext/object/instance_variables_test.rb b/activesupport/test/core_ext/object/instance_variables_test.rb
index cf1fe5dfa4..9052d209a3 100644
--- a/activesupport/test/core_ext/object/instance_variables_test.rb
+++ b/activesupport/test/core_ext/object/instance_variables_test.rb
@@ -23,7 +23,7 @@ class ObjectInstanceVariableTest < ActiveSupport::TestCase
   end
 
   def test_instance_exec_with_frozen_obj
-    assert_equal %w(olleh goodbye), "hello".freeze.instance_exec("goodbye") { |v| [reverse, v] }
+    assert_equal %w(olleh goodbye), "hello".instance_exec("goodbye") { |v| [reverse, v] }
   end
 
   def test_instance_exec_nested
diff --git a/activesupport/test/core_ext/string_ext_test.rb b/activesupport/test/core_ext/string_ext_test.rb
index a26473dc84..aa120a6f9a 100644
--- a/activesupport/test/core_ext/string_ext_test.rb
+++ b/activesupport/test/core_ext/string_ext_test.rb
@@ -25,7 +25,7 @@ class StringInflectionsTest < ActiveSupport::TestCase
   end
 
   def test_strip_heredoc_on_a_frozen_string
-    assert "".freeze.strip_heredoc.frozen?
+    assert "".strip_heredoc.frozen?
   end
 
   def test_strip_heredoc_on_a_string_with_no_lines