Merge pull request #29540 from kirs/rubocop-frozen-string

Enforce frozen string in Rubocop

249 files changed, 249 insertions, 0 deletions

diff --git a/activerecord/test/cases/adapter_test.rb b/activerecord/test/cases/adapter_test.rb
index a1fb6427f9..dd891cb2ed 100644
--- a/activerecord/test/cases/adapter_test.rb
+++ b/activerecord/test/cases/adapter_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/book"
 require "models/post"
diff --git a/activerecord/test/cases/adapters/mysql2/active_schema_test.rb b/activerecord/test/cases/adapters/mysql2/active_schema_test.rb
index 67e1efde27..fdf83aaf88 100644
--- a/activerecord/test/cases/adapters/mysql2/active_schema_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/active_schema_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/connection_helper"
 
diff --git a/activerecord/test/cases/adapters/mysql2/bind_parameter_test.rb b/activerecord/test/cases/adapters/mysql2/bind_parameter_test.rb
index 8f7c803a21..9f3d1459f7 100644
--- a/activerecord/test/cases/adapters/mysql2/bind_parameter_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/bind_parameter_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 
diff --git a/activerecord/test/cases/adapters/mysql2/boolean_test.rb b/activerecord/test/cases/adapters/mysql2/boolean_test.rb
index 58698d59db..9267d15def 100644
--- a/activerecord/test/cases/adapters/mysql2/boolean_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/boolean_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class Mysql2BooleanTest < ActiveRecord::Mysql2TestCase
diff --git a/activerecord/test/cases/adapters/mysql2/case_sensitivity_test.rb b/activerecord/test/cases/adapters/mysql2/case_sensitivity_test.rb
index 50ba9ab831..65dc369213 100644
--- a/activerecord/test/cases/adapters/mysql2/case_sensitivity_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/case_sensitivity_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class Mysql2CaseSensitivityTest < ActiveRecord::Mysql2TestCase
diff --git a/activerecord/test/cases/adapters/mysql2/charset_collation_test.rb b/activerecord/test/cases/adapters/mysql2/charset_collation_test.rb
index e4a6ed5482..e77f4a90d4 100644
--- a/activerecord/test/cases/adapters/mysql2/charset_collation_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/charset_collation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/adapters/mysql2/connection_test.rb b/activerecord/test/cases/adapters/mysql2/connection_test.rb
index a2faf43b0d..c5ff145e74 100644
--- a/activerecord/test/cases/adapters/mysql2/connection_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/connection_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/connection_helper"
 
diff --git a/activerecord/test/cases/adapters/mysql2/datetime_precision_quoting_test.rb b/activerecord/test/cases/adapters/mysql2/datetime_precision_quoting_test.rb
index c131a5169c..86e72c149c 100644
--- a/activerecord/test/cases/adapters/mysql2/datetime_precision_quoting_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/datetime_precision_quoting_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class Mysql2DatetimePrecisionQuotingTest < ActiveRecord::Mysql2TestCase
diff --git a/activerecord/test/cases/adapters/mysql2/enum_test.rb b/activerecord/test/cases/adapters/mysql2/enum_test.rb
index 7ad3e3ca2d..b811179c1b 100644
--- a/activerecord/test/cases/adapters/mysql2/enum_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/enum_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class Mysql2EnumTest < ActiveRecord::Mysql2TestCase
diff --git a/activerecord/test/cases/adapters/mysql2/explain_test.rb b/activerecord/test/cases/adapters/mysql2/explain_test.rb
index 7916921e5a..84c15af08d 100644
--- a/activerecord/test/cases/adapters/mysql2/explain_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/explain_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/developer"
 require "models/computer"
diff --git a/activerecord/test/cases/adapters/mysql2/json_test.rb b/activerecord/test/cases/adapters/mysql2/json_test.rb
index 26c69edc7b..2d39db4ce2 100644
--- a/activerecord/test/cases/adapters/mysql2/json_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/json_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "cases/json_shared_test_cases"
 
diff --git a/activerecord/test/cases/adapters/mysql2/mysql2_adapter_test.rb b/activerecord/test/cases/adapters/mysql2/mysql2_adapter_test.rb
index 565130c38f..7ba388bee1 100644
--- a/activerecord/test/cases/adapters/mysql2/mysql2_adapter_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/mysql2_adapter_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/ddl_helper"
 
diff --git a/activerecord/test/cases/adapters/mysql2/schema_migrations_test.rb b/activerecord/test/cases/adapters/mysql2/schema_migrations_test.rb
index 251a50e41e..4a421e2b91 100644
--- a/activerecord/test/cases/adapters/mysql2/schema_migrations_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/schema_migrations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class SchemaMigrationsTest < ActiveRecord::Mysql2TestCase
diff --git a/activerecord/test/cases/adapters/mysql2/schema_test.rb b/activerecord/test/cases/adapters/mysql2/schema_test.rb
index 1fad5585de..c4bf58c13e 100644
--- a/activerecord/test/cases/adapters/mysql2/schema_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/schema_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/comment"
diff --git a/activerecord/test/cases/adapters/mysql2/sp_test.rb b/activerecord/test/cases/adapters/mysql2/sp_test.rb
index 4182532535..d4c4d02f79 100644
--- a/activerecord/test/cases/adapters/mysql2/sp_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/sp_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/reply"
diff --git a/activerecord/test/cases/adapters/mysql2/sql_types_test.rb b/activerecord/test/cases/adapters/mysql2/sql_types_test.rb
index d6e7f29a5c..c412166451 100644
--- a/activerecord/test/cases/adapters/mysql2/sql_types_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/sql_types_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class Mysql2SqlTypesTest < ActiveRecord::Mysql2TestCase
diff --git a/activerecord/test/cases/adapters/mysql2/table_options_test.rb b/activerecord/test/cases/adapters/mysql2/table_options_test.rb
index 61a8ce9bc0..54da2195d1 100644
--- a/activerecord/test/cases/adapters/mysql2/table_options_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/table_options_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/adapters/mysql2/transaction_test.rb b/activerecord/test/cases/adapters/mysql2/transaction_test.rb
index 16101e38cb..e447e6ec83 100644
--- a/activerecord/test/cases/adapters/mysql2/transaction_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/transaction_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/connection_helper"
 
diff --git a/activerecord/test/cases/adapters/mysql2/unsigned_type_test.rb b/activerecord/test/cases/adapters/mysql2/unsigned_type_test.rb
index 71dcfaa241..1703e8fef7 100644
--- a/activerecord/test/cases/adapters/mysql2/unsigned_type_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/unsigned_type_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/adapters/mysql2/virtual_column_test.rb b/activerecord/test/cases/adapters/mysql2/virtual_column_test.rb
index 442a4fb7b5..85e283bfe1 100644
--- a/activerecord/test/cases/adapters/mysql2/virtual_column_test.rb
+++ b/activerecord/test/cases/adapters/mysql2/virtual_column_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/adapters/postgresql/active_schema_test.rb b/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
index b787de8453..441e84a117 100644
--- a/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/active_schema_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class PostgresqlActiveSchemaTest < ActiveRecord::PostgreSQLTestCase
diff --git a/activerecord/test/cases/adapters/postgresql/array_test.rb b/activerecord/test/cases/adapters/postgresql/array_test.rb
index 121c62dadf..a642145726 100644
--- a/activerecord/test/cases/adapters/postgresql/array_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/array_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 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 7712e809a2..d7ed0aa8dd 100644
--- a/activerecord/test/cases/adapters/postgresql/bit_string_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/bit_string_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 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 65baed34e9..39d76de770 100644
--- a/activerecord/test/cases/adapters/postgresql/bytea_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/bytea_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/adapters/postgresql/case_insensitive_test.rb b/activerecord/test/cases/adapters/postgresql/case_insensitive_test.rb
index 03b44feab6..b6db6e5e28 100644
--- a/activerecord/test/cases/adapters/postgresql/case_insensitive_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/case_insensitive_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class PostgresqlCaseInsensitiveTest < ActiveRecord::PostgreSQLTestCase
diff --git a/activerecord/test/cases/adapters/postgresql/change_schema_test.rb b/activerecord/test/cases/adapters/postgresql/change_schema_test.rb
index ea642069d2..9d7fddfc02 100644
--- a/activerecord/test/cases/adapters/postgresql/change_schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/change_schema_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/adapters/postgresql/cidr_test.rb b/activerecord/test/cases/adapters/postgresql/cidr_test.rb
index 52f2a0096c..fccd8b3c7b 100644
--- a/activerecord/test/cases/adapters/postgresql/cidr_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/cidr_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "ipaddr"
 
diff --git a/activerecord/test/cases/adapters/postgresql/citext_test.rb b/activerecord/test/cases/adapters/postgresql/citext_test.rb
index ca95e4b626..ffdd2983c6 100644
--- a/activerecord/test/cases/adapters/postgresql/citext_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/citext_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/adapters/postgresql/collation_test.rb b/activerecord/test/cases/adapters/postgresql/collation_test.rb
index a603221d8f..2929c9ad94 100644
--- a/activerecord/test/cases/adapters/postgresql/collation_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/collation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 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 1da2a9e2ac..9eb422a8a3 100644
--- a/activerecord/test/cases/adapters/postgresql/composite_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/composite_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/connection_helper"
 
diff --git a/activerecord/test/cases/adapters/postgresql/connection_test.rb b/activerecord/test/cases/adapters/postgresql/connection_test.rb
index 32afe331fa..3adae7e146 100644
--- a/activerecord/test/cases/adapters/postgresql/connection_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/connection_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/connection_helper"
 
diff --git a/activerecord/test/cases/adapters/postgresql/datatype_test.rb b/activerecord/test/cases/adapters/postgresql/datatype_test.rb
index 0725fde5ae..f947868898 100644
--- a/activerecord/test/cases/adapters/postgresql/datatype_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/datatype_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/ddl_helper"
 
diff --git a/activerecord/test/cases/adapters/postgresql/domain_test.rb b/activerecord/test/cases/adapters/postgresql/domain_test.rb
index f1eb8adb15..b16e0f9265 100644
--- a/activerecord/test/cases/adapters/postgresql/domain_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/domain_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 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 5e5a3158ba..0f8ab8ab23 100644
--- a/activerecord/test/cases/adapters/postgresql/enum_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/enum_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/connection_helper"
 
diff --git a/activerecord/test/cases/adapters/postgresql/explain_test.rb b/activerecord/test/cases/adapters/postgresql/explain_test.rb
index d79fbccf47..8a0cf440fd 100644
--- a/activerecord/test/cases/adapters/postgresql/explain_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/explain_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/developer"
 require "models/computer"
diff --git a/activerecord/test/cases/adapters/postgresql/extension_migration_test.rb b/activerecord/test/cases/adapters/postgresql/extension_migration_test.rb
index b56c226763..ba2b4e1fbf 100644
--- a/activerecord/test/cases/adapters/postgresql/extension_migration_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/extension_migration_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class PostgresqlExtensionMigrationTest < ActiveRecord::PostgreSQLTestCase
diff --git a/activerecord/test/cases/adapters/postgresql/full_text_test.rb b/activerecord/test/cases/adapters/postgresql/full_text_test.rb
index 5ddfe32007..fa8aadd224 100644
--- a/activerecord/test/cases/adapters/postgresql/full_text_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/full_text_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 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 3b6840a1c9..34836b2421 100644
--- a/activerecord/test/cases/adapters/postgresql/geometric_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/geometric_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 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 f9cce10fb8..b547868b57 100644
--- a/activerecord/test/cases/adapters/postgresql/hstore_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/hstore_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/adapters/postgresql/infinity_test.rb b/activerecord/test/cases/adapters/postgresql/infinity_test.rb
index b9e177e6ec..df5c688881 100644
--- a/activerecord/test/cases/adapters/postgresql/infinity_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/infinity_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class PostgresqlInfinityTest < ActiveRecord::PostgreSQLTestCase
diff --git a/activerecord/test/cases/adapters/postgresql/integer_test.rb b/activerecord/test/cases/adapters/postgresql/integer_test.rb
index b4e55964b9..5557e869ad 100644
--- a/activerecord/test/cases/adapters/postgresql/integer_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/integer_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "active_support/core_ext/numeric/bytes"
 
diff --git a/activerecord/test/cases/adapters/postgresql/json_test.rb b/activerecord/test/cases/adapters/postgresql/json_test.rb
index 6aa60630c2..4438f349cc 100644
--- a/activerecord/test/cases/adapters/postgresql/json_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/json_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "cases/json_shared_test_cases"
 
diff --git a/activerecord/test/cases/adapters/postgresql/ltree_test.rb b/activerecord/test/cases/adapters/postgresql/ltree_test.rb
index 2b5ac1cac6..447d68316c 100644
--- a/activerecord/test/cases/adapters/postgresql/ltree_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/ltree_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 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 ea060345a7..f5c50a80c2 100644
--- a/activerecord/test/cases/adapters/postgresql/money_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/money_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 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 a33b0ef8a7..2bbfb292c4 100644
--- a/activerecord/test/cases/adapters/postgresql/network_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/network_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/adapters/postgresql/numbers_test.rb b/activerecord/test/cases/adapters/postgresql/numbers_test.rb
index bfb2b7c27a..82edf7db3f 100644
--- a/activerecord/test/cases/adapters/postgresql/numbers_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/numbers_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class PostgresqlNumberTest < ActiveRecord::PostgreSQLTestCase
diff --git a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
index 76e0ad60fe..7c7bb0a942 100644
--- a/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/postgresql_adapter_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/ddl_helper"
 require "support/connection_helper"
diff --git a/activerecord/test/cases/adapters/postgresql/prepared_statements_disabled_test.rb b/activerecord/test/cases/adapters/postgresql/prepared_statements_disabled_test.rb
index 8c62690866..0120e33f70 100644
--- a/activerecord/test/cases/adapters/postgresql/prepared_statements_disabled_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/prepared_statements_disabled_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/computer"
 require "models/developer"
diff --git a/activerecord/test/cases/adapters/postgresql/quoting_test.rb b/activerecord/test/cases/adapters/postgresql/quoting_test.rb
index a1e966b915..1205559558 100644
--- a/activerecord/test/cases/adapters/postgresql/quoting_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/quoting_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/adapters/postgresql/range_test.rb b/activerecord/test/cases/adapters/postgresql/range_test.rb
index f411884dfd..8de162a8a1 100644
--- a/activerecord/test/cases/adapters/postgresql/range_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/range_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/connection_helper"
 
diff --git a/activerecord/test/cases/adapters/postgresql/referential_integrity_test.rb b/activerecord/test/cases/adapters/postgresql/referential_integrity_test.rb
index 0ff04bfa27..0b17c141c8 100644
--- a/activerecord/test/cases/adapters/postgresql/referential_integrity_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/referential_integrity_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/connection_helper"
 
diff --git a/activerecord/test/cases/adapters/postgresql/rename_table_test.rb b/activerecord/test/cases/adapters/postgresql/rename_table_test.rb
index e9e7f717ac..5b253999d5 100644
--- a/activerecord/test/cases/adapters/postgresql/rename_table_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/rename_table_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class PostgresqlRenameTableTest < ActiveRecord::PostgreSQLTestCase
diff --git a/activerecord/test/cases/adapters/postgresql/schema_authorization_test.rb b/activerecord/test/cases/adapters/postgresql/schema_authorization_test.rb
index f86a76e08a..db7d8ba751 100644
--- a/activerecord/test/cases/adapters/postgresql/schema_authorization_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/schema_authorization_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class SchemaThing < ActiveRecord::Base
diff --git a/activerecord/test/cases/adapters/postgresql/schema_test.rb b/activerecord/test/cases/adapters/postgresql/schema_test.rb
index f6b957476b..5438665d42 100644
--- a/activerecord/test/cases/adapters/postgresql/schema_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/schema_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/default"
 require "support/schema_dumping_helper"
diff --git a/activerecord/test/cases/adapters/postgresql/serial_test.rb b/activerecord/test/cases/adapters/postgresql/serial_test.rb
index d711b3b729..4930d3f67a 100644
--- a/activerecord/test/cases/adapters/postgresql/serial_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/serial_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/adapters/postgresql/statement_pool_test.rb b/activerecord/test/cases/adapters/postgresql/statement_pool_test.rb
index 146b619a4b..73cf91425b 100644
--- a/activerecord/test/cases/adapters/postgresql/statement_pool_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/statement_pool_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/adapters/postgresql/timestamp_test.rb b/activerecord/test/cases/adapters/postgresql/timestamp_test.rb
index 962450aada..c7dec25f3a 100644
--- a/activerecord/test/cases/adapters/postgresql/timestamp_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/timestamp_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/developer"
 require "models/topic"
diff --git a/activerecord/test/cases/adapters/postgresql/transaction_test.rb b/activerecord/test/cases/adapters/postgresql/transaction_test.rb
index 9b42d0383d..c1b19c11f5 100644
--- a/activerecord/test/cases/adapters/postgresql/transaction_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/transaction_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/connection_helper"
 require "concurrent/atomic/cyclic_barrier"
diff --git a/activerecord/test/cases/adapters/postgresql/type_lookup_test.rb b/activerecord/test/cases/adapters/postgresql/type_lookup_test.rb
index 784d77a8d1..688117722b 100644
--- a/activerecord/test/cases/adapters/postgresql/type_lookup_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/type_lookup_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class PostgresqlTypeLookupTest < ActiveRecord::PostgreSQLTestCase
diff --git a/activerecord/test/cases/adapters/postgresql/utils_test.rb b/activerecord/test/cases/adapters/postgresql/utils_test.rb
index 9f9e3bda2f..1a655d7843 100644
--- a/activerecord/test/cases/adapters/postgresql/utils_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/utils_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "active_record/connection_adapters/postgresql/utils"
 
diff --git a/activerecord/test/cases/adapters/postgresql/uuid_test.rb b/activerecord/test/cases/adapters/postgresql/uuid_test.rb
index 8eddd81c38..49c570c917 100644
--- a/activerecord/test/cases/adapters/postgresql/uuid_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/uuid_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 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 826b384fb3..b0720b5a6e 100644
--- a/activerecord/test/cases/adapters/postgresql/xml_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/xml_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/adapters/sqlite3/collation_test.rb b/activerecord/test/cases/adapters/sqlite3/collation_test.rb
index dd88ed3656..f3cbb408f1 100644
--- a/activerecord/test/cases/adapters/sqlite3/collation_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/collation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/adapters/sqlite3/copy_table_test.rb b/activerecord/test/cases/adapters/sqlite3/copy_table_test.rb
index e1cfd703e8..cc1f74ed41 100644
--- a/activerecord/test/cases/adapters/sqlite3/copy_table_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/copy_table_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class CopyTableTest < ActiveRecord::SQLite3TestCase
diff --git a/activerecord/test/cases/adapters/sqlite3/explain_test.rb b/activerecord/test/cases/adapters/sqlite3/explain_test.rb
index 29d97ae78c..a3f6299756 100644
--- a/activerecord/test/cases/adapters/sqlite3/explain_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/explain_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/developer"
 require "models/computer"
diff --git a/activerecord/test/cases/adapters/sqlite3/quoting_test.rb b/activerecord/test/cases/adapters/sqlite3/quoting_test.rb
index aefbb309e6..0a5bf7754c 100644
--- a/activerecord/test/cases/adapters/sqlite3/quoting_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/quoting_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "bigdecimal"
 require "securerandom"
diff --git a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
index cf0c37f70c..bc6605682c 100644
--- a/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 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 b1b4463bf1..d23a7ac532 100644
--- a/activerecord/test/cases/adapters/sqlite3/sqlite3_create_folder_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/sqlite3_create_folder_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/owner"
 
diff --git a/activerecord/test/cases/adapters/sqlite3/statement_pool_test.rb b/activerecord/test/cases/adapters/sqlite3/statement_pool_test.rb
index 37ff973397..76841c235a 100644
--- a/activerecord/test/cases/adapters/sqlite3/statement_pool_test.rb
+++ b/activerecord/test/cases/adapters/sqlite3/statement_pool_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class SQLite3StatementPoolTest < ActiveRecord::SQLite3TestCase
diff --git a/activerecord/test/cases/aggregations_test.rb b/activerecord/test/cases/aggregations_test.rb
index f8136fde72..97be9c447a 100644
--- a/activerecord/test/cases/aggregations_test.rb
+++ b/activerecord/test/cases/aggregations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/customer"
 
diff --git a/activerecord/test/cases/ar_schema_test.rb b/activerecord/test/cases/ar_schema_test.rb
index 5b608d8e83..aaae3736a9 100644
--- a/activerecord/test/cases/ar_schema_test.rb
+++ b/activerecord/test/cases/ar_schema_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class ActiveRecordSchemaTest < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/associations/association_scope_test.rb b/activerecord/test/cases/associations/association_scope_test.rb
index c54542ff7b..a57eb78a14 100644
--- a/activerecord/test/cases/associations/association_scope_test.rb
+++ b/activerecord/test/cases/associations/association_scope_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/author"
diff --git a/activerecord/test/cases/associations/belongs_to_associations_test.rb b/activerecord/test/cases/associations/belongs_to_associations_test.rb
index a727cc6e60..af3f40974d 100644
--- a/activerecord/test/cases/associations/belongs_to_associations_test.rb
+++ b/activerecord/test/cases/associations/belongs_to_associations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/developer"
 require "models/project"
diff --git a/activerecord/test/cases/associations/bidirectional_destroy_dependencies_test.rb b/activerecord/test/cases/associations/bidirectional_destroy_dependencies_test.rb
index 8a0e041864..eee327a0bc 100644
--- a/activerecord/test/cases/associations/bidirectional_destroy_dependencies_test.rb
+++ b/activerecord/test/cases/associations/bidirectional_destroy_dependencies_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/content"
 
diff --git a/activerecord/test/cases/associations/callbacks_test.rb b/activerecord/test/cases/associations/callbacks_test.rb
index f9d1e44595..b91fb5b7ed 100644
--- a/activerecord/test/cases/associations/callbacks_test.rb
+++ b/activerecord/test/cases/associations/callbacks_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/author"
diff --git a/activerecord/test/cases/associations/cascaded_eager_loading_test.rb b/activerecord/test/cases/associations/cascaded_eager_loading_test.rb
index 7b0445025c..ea2582b507 100644
--- a/activerecord/test/cases/associations/cascaded_eager_loading_test.rb
+++ b/activerecord/test/cases/associations/cascaded_eager_loading_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/comment"
diff --git a/activerecord/test/cases/associations/eager_load_includes_full_sti_class_test.rb b/activerecord/test/cases/associations/eager_load_includes_full_sti_class_test.rb
index 61f39b4136..f6de62b1af 100644
--- a/activerecord/test/cases/associations/eager_load_includes_full_sti_class_test.rb
+++ b/activerecord/test/cases/associations/eager_load_includes_full_sti_class_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/tagging"
diff --git a/activerecord/test/cases/associations/eager_load_nested_include_test.rb b/activerecord/test/cases/associations/eager_load_nested_include_test.rb
index e9f551b6b2..83c85cd022 100644
--- a/activerecord/test/cases/associations/eager_load_nested_include_test.rb
+++ b/activerecord/test/cases/associations/eager_load_nested_include_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/tag"
diff --git a/activerecord/test/cases/associations/eager_singularization_test.rb b/activerecord/test/cases/associations/eager_singularization_test.rb
index 16eff15026..860bb9ac54 100644
--- a/activerecord/test/cases/associations/eager_singularization_test.rb
+++ b/activerecord/test/cases/associations/eager_singularization_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class EagerSingularizationTest < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/associations/eager_test.rb b/activerecord/test/cases/associations/eager_test.rb
index 55b294cfaa..e0b137304b 100644
--- a/activerecord/test/cases/associations/eager_test.rb
+++ b/activerecord/test/cases/associations/eager_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/tagging"
diff --git a/activerecord/test/cases/associations/extension_test.rb b/activerecord/test/cases/associations/extension_test.rb
index f707a170f5..d2f21583a7 100644
--- a/activerecord/test/cases/associations/extension_test.rb
+++ b/activerecord/test/cases/associations/extension_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/comment"
diff --git a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
index f73005b3cb..fa40bd2ff8 100644
--- a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/developer"
 require "models/computer"
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index a7e16af88d..5ad1e2aecc 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/developer"
 require "models/computer"
diff --git a/activerecord/test/cases/associations/has_many_through_associations_test.rb b/activerecord/test/cases/associations/has_many_through_associations_test.rb
index 1c2138a3d0..6794428688 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/person"
diff --git a/activerecord/test/cases/associations/has_one_associations_test.rb b/activerecord/test/cases/associations/has_one_associations_test.rb
index bf3b8dcd63..545eec7e5d 100644
--- a/activerecord/test/cases/associations/has_one_associations_test.rb
+++ b/activerecord/test/cases/associations/has_one_associations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/developer"
 require "models/computer"
diff --git a/activerecord/test/cases/associations/has_one_through_associations_test.rb b/activerecord/test/cases/associations/has_one_through_associations_test.rb
index 28b883586d..0a74a9e710 100644
--- a/activerecord/test/cases/associations/has_one_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_one_through_associations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/club"
 require "models/member_type"
diff --git a/activerecord/test/cases/associations/inner_join_association_test.rb b/activerecord/test/cases/associations/inner_join_association_test.rb
index ddf5bc6f0b..6fff4171c8 100644
--- a/activerecord/test/cases/associations/inner_join_association_test.rb
+++ b/activerecord/test/cases/associations/inner_join_association_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/comment"
diff --git a/activerecord/test/cases/associations/inverse_associations_test.rb b/activerecord/test/cases/associations/inverse_associations_test.rb
index 8e3087e7ca..95ba6bdf8a 100644
--- a/activerecord/test/cases/associations/inverse_associations_test.rb
+++ b/activerecord/test/cases/associations/inverse_associations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/man"
 require "models/face"
diff --git a/activerecord/test/cases/associations/join_model_test.rb b/activerecord/test/cases/associations/join_model_test.rb
index c078cef064..c2758b30a1 100644
--- a/activerecord/test/cases/associations/join_model_test.rb
+++ b/activerecord/test/cases/associations/join_model_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/tag"
 require "models/tagging"
diff --git a/activerecord/test/cases/associations/left_outer_join_association_test.rb b/activerecord/test/cases/associations/left_outer_join_association_test.rb
index 6d3757f467..68c9286972 100644
--- a/activerecord/test/cases/associations/left_outer_join_association_test.rb
+++ b/activerecord/test/cases/associations/left_outer_join_association_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/comment"
diff --git a/activerecord/test/cases/associations/nested_through_associations_test.rb b/activerecord/test/cases/associations/nested_through_associations_test.rb
index 67ff7355b3..90b2d4bc07 100644
--- a/activerecord/test/cases/associations/nested_through_associations_test.rb
+++ b/activerecord/test/cases/associations/nested_through_associations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/author"
 require "models/post"
diff --git a/activerecord/test/cases/associations/required_test.rb b/activerecord/test/cases/associations/required_test.rb
index 45e1803858..6cf2d8ac12 100644
--- a/activerecord/test/cases/associations/required_test.rb
+++ b/activerecord/test/cases/associations/required_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class RequiredAssociationsTest < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/associations_test.rb b/activerecord/test/cases/associations_test.rb
index 2eb31326a5..ba2f4c11c8 100644
--- a/activerecord/test/cases/associations_test.rb
+++ b/activerecord/test/cases/associations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/computer"
 require "models/developer"
diff --git a/activerecord/test/cases/attribute_decorators_test.rb b/activerecord/test/cases/attribute_decorators_test.rb
index cfa6ed1da6..eb8efab6a5 100644
--- a/activerecord/test/cases/attribute_decorators_test.rb
+++ b/activerecord/test/cases/attribute_decorators_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/attribute_methods/read_test.rb b/activerecord/test/cases/attribute_methods/read_test.rb
index 1fc63a49d4..a366144e17 100644
--- a/activerecord/test/cases/attribute_methods/read_test.rb
+++ b/activerecord/test/cases/attribute_methods/read_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/attribute_methods_test.rb b/activerecord/test/cases/attribute_methods_test.rb
index 4d24a980dc..1f3a3652d7 100644
--- a/activerecord/test/cases/attribute_methods_test.rb
+++ b/activerecord/test/cases/attribute_methods_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/minimalistic"
 require "models/developer"
diff --git a/activerecord/test/cases/attribute_set_test.rb b/activerecord/test/cases/attribute_set_test.rb
index bd4b200735..80c67f171b 100644
--- a/activerecord/test/cases/attribute_set_test.rb
+++ b/activerecord/test/cases/attribute_set_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/attribute_test.rb b/activerecord/test/cases/attribute_test.rb
index e856d551c0..ed9fb1b57b 100644
--- a/activerecord/test/cases/attribute_test.rb
+++ b/activerecord/test/cases/attribute_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/attributes_test.rb b/activerecord/test/cases/attributes_test.rb
index 3705a6be89..8aa515fe6e 100644
--- a/activerecord/test/cases/attributes_test.rb
+++ b/activerecord/test/cases/attributes_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class OverloadedType < ActiveRecord::Base
diff --git a/activerecord/test/cases/autosave_association_test.rb b/activerecord/test/cases/autosave_association_test.rb
index 2203aa1788..db2a19ea62 100644
--- a/activerecord/test/cases/autosave_association_test.rb
+++ b/activerecord/test/cases/autosave_association_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/bird"
 require "models/post"
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index dc32e995a4..a26a4bbb61 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/author"
diff --git a/activerecord/test/cases/batches_test.rb b/activerecord/test/cases/batches_test.rb
index 1a66b82b2e..beae679542 100644
--- a/activerecord/test/cases/batches_test.rb
+++ b/activerecord/test/cases/batches_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/subscriber"
diff --git a/activerecord/test/cases/binary_test.rb b/activerecord/test/cases/binary_test.rb
index f6ac7990d1..89301563f9 100644
--- a/activerecord/test/cases/binary_test.rb
+++ b/activerecord/test/cases/binary_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 # Without using prepared statements, it makes no sense to test
diff --git a/activerecord/test/cases/bind_parameter_test.rb b/activerecord/test/cases/bind_parameter_test.rb
index 5af44c27eb..8504f586cc 100644
--- a/activerecord/test/cases/bind_parameter_test.rb
+++ b/activerecord/test/cases/bind_parameter_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/author"
diff --git a/activerecord/test/cases/cache_key_test.rb b/activerecord/test/cases/cache_key_test.rb
index 7b8264e6e8..f0a1bb9e22 100644
--- a/activerecord/test/cases/cache_key_test.rb
+++ b/activerecord/test/cases/cache_key_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/calculations_test.rb b/activerecord/test/cases/calculations_test.rb
index 80baaac30a..478b9fe742 100644
--- a/activerecord/test/cases/calculations_test.rb
+++ b/activerecord/test/cases/calculations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/book"
 require "models/club"
diff --git a/activerecord/test/cases/callbacks_test.rb b/activerecord/test/cases/callbacks_test.rb
index b3c86586d0..55deaa6947 100644
--- a/activerecord/test/cases/callbacks_test.rb
+++ b/activerecord/test/cases/callbacks_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/developer"
 require "models/computer"
diff --git a/activerecord/test/cases/clone_test.rb b/activerecord/test/cases/clone_test.rb
index b89294c094..fa0f53676e 100644
--- a/activerecord/test/cases/clone_test.rb
+++ b/activerecord/test/cases/clone_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 
diff --git a/activerecord/test/cases/coders/json_test.rb b/activerecord/test/cases/coders/json_test.rb
index d22d93d129..95e6fb3e7b 100644
--- a/activerecord/test/cases/coders/json_test.rb
+++ b/activerecord/test/cases/coders/json_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/coders/yaml_column_test.rb b/activerecord/test/cases/coders/yaml_column_test.rb
index a26a72712d..e3e85a58a4 100644
--- a/activerecord/test/cases/coders/yaml_column_test.rb
+++ b/activerecord/test/cases/coders/yaml_column_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/collection_cache_key_test.rb b/activerecord/test/cases/collection_cache_key_test.rb
index f344c77691..2d10a68416 100644
--- a/activerecord/test/cases/collection_cache_key_test.rb
+++ b/activerecord/test/cases/collection_cache_key_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/computer"
 require "models/developer"
diff --git a/activerecord/test/cases/column_alias_test.rb b/activerecord/test/cases/column_alias_test.rb
index 9893ba9580..506ae05756 100644
--- a/activerecord/test/cases/column_alias_test.rb
+++ b/activerecord/test/cases/column_alias_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 
diff --git a/activerecord/test/cases/column_definition_test.rb b/activerecord/test/cases/column_definition_test.rb
index 90c8d21c43..fcb0952c1c 100644
--- a/activerecord/test/cases/column_definition_test.rb
+++ b/activerecord/test/cases/column_definition_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/comment_test.rb b/activerecord/test/cases/comment_test.rb
index c23be52a6c..5c91ac347c 100644
--- a/activerecord/test/cases/comment_test.rb
+++ b/activerecord/test/cases/comment_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/connection_adapters/adapter_leasing_test.rb b/activerecord/test/cases/connection_adapters/adapter_leasing_test.rb
index 64189381cb..4f88b129af 100644
--- a/activerecord/test/cases/connection_adapters/adapter_leasing_test.rb
+++ b/activerecord/test/cases/connection_adapters/adapter_leasing_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/connection_adapters/connection_handler_test.rb b/activerecord/test/cases/connection_adapters/connection_handler_test.rb
index 2a71f08d90..f8725ddb01 100644
--- a/activerecord/test/cases/connection_adapters/connection_handler_test.rb
+++ b/activerecord/test/cases/connection_adapters/connection_handler_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/connection_adapters/connection_specification_test.rb b/activerecord/test/cases/connection_adapters/connection_specification_test.rb
index 10a3521c79..40998c06bf 100644
--- a/activerecord/test/cases/connection_adapters/connection_specification_test.rb
+++ b/activerecord/test/cases/connection_adapters/connection_specification_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb b/activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb
index 8faa67255d..7c98c80e39 100644
--- a/activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb
+++ b/activerecord/test/cases/connection_adapters/merge_and_resolve_default_url_config_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/connection_adapters/mysql_type_lookup_test.rb b/activerecord/test/cases/connection_adapters/mysql_type_lookup_test.rb
index 3657b8340d..133632bac9 100644
--- a/activerecord/test/cases/connection_adapters/mysql_type_lookup_test.rb
+++ b/activerecord/test/cases/connection_adapters/mysql_type_lookup_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 if current_adapter?(:Mysql2Adapter)
diff --git a/activerecord/test/cases/connection_adapters/schema_cache_test.rb b/activerecord/test/cases/connection_adapters/schema_cache_test.rb
index 106323ccc9..3370818616 100644
--- a/activerecord/test/cases/connection_adapters/schema_cache_test.rb
+++ b/activerecord/test/cases/connection_adapters/schema_cache_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/connection_adapters/type_lookup_test.rb b/activerecord/test/cases/connection_adapters/type_lookup_test.rb
index a348c2d783..251483da44 100644
--- a/activerecord/test/cases/connection_adapters/type_lookup_test.rb
+++ b/activerecord/test/cases/connection_adapters/type_lookup_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 unless current_adapter?(:PostgreSQLAdapter) # PostgreSQL does not use type strings for lookup
diff --git a/activerecord/test/cases/connection_management_test.rb b/activerecord/test/cases/connection_management_test.rb
index d1e946d401..9bd0aab981 100644
--- a/activerecord/test/cases/connection_management_test.rb
+++ b/activerecord/test/cases/connection_management_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "rack"
 
diff --git a/activerecord/test/cases/connection_pool_test.rb b/activerecord/test/cases/connection_pool_test.rb
index 00a0187b57..adbd158e7a 100644
--- a/activerecord/test/cases/connection_pool_test.rb
+++ b/activerecord/test/cases/connection_pool_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "concurrent/atomic/count_down_latch"
 
diff --git a/activerecord/test/cases/connection_specification/resolver_test.rb b/activerecord/test/cases/connection_specification/resolver_test.rb
index 13b5bae13c..3d97281627 100644
--- a/activerecord/test/cases/connection_specification/resolver_test.rb
+++ b/activerecord/test/cases/connection_specification/resolver_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/core_test.rb b/activerecord/test/cases/core_test.rb
index 936f26ce04..5cf962c39d 100644
--- a/activerecord/test/cases/core_test.rb
+++ b/activerecord/test/cases/core_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/person"
 require "models/topic"
diff --git a/activerecord/test/cases/counter_cache_test.rb b/activerecord/test/cases/counter_cache_test.rb
index 46d7526cc0..14800e6b91 100644
--- a/activerecord/test/cases/counter_cache_test.rb
+++ b/activerecord/test/cases/counter_cache_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/car"
diff --git a/activerecord/test/cases/custom_locking_test.rb b/activerecord/test/cases/custom_locking_test.rb
index 15c8b684e4..e170843952 100644
--- a/activerecord/test/cases/custom_locking_test.rb
+++ b/activerecord/test/cases/custom_locking_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/person"
 
diff --git a/activerecord/test/cases/database_statements_test.rb b/activerecord/test/cases/database_statements_test.rb
index 66035865be..5df028d397 100644
--- a/activerecord/test/cases/database_statements_test.rb
+++ b/activerecord/test/cases/database_statements_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class DatabaseStatementsTest < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/date_test.rb b/activerecord/test/cases/date_test.rb
index 2edc0415cd..202100ff69 100644
--- a/activerecord/test/cases/date_test.rb
+++ b/activerecord/test/cases/date_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 
diff --git a/activerecord/test/cases/date_time_precision_test.rb b/activerecord/test/cases/date_time_precision_test.rb
index e4a2f9ee17..12b1858991 100644
--- a/activerecord/test/cases/date_time_precision_test.rb
+++ b/activerecord/test/cases/date_time_precision_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/date_time_test.rb b/activerecord/test/cases/date_time_test.rb
index ad7da9de70..8753c95641 100644
--- a/activerecord/test/cases/date_time_test.rb
+++ b/activerecord/test/cases/date_time_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/task"
diff --git a/activerecord/test/cases/defaults_test.rb b/activerecord/test/cases/defaults_test.rb
index 996d298689..30cfa0744f 100644
--- a/activerecord/test/cases/defaults_test.rb
+++ b/activerecord/test/cases/defaults_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 require "models/default"
diff --git a/activerecord/test/cases/dirty_test.rb b/activerecord/test/cases/dirty_test.rb
index f72e0d2ead..cc2724502b 100644
--- a/activerecord/test/cases/dirty_test.rb
+++ b/activerecord/test/cases/dirty_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"    # For booleans
 require "models/pirate"   # For timestamps
diff --git a/activerecord/test/cases/disconnected_test.rb b/activerecord/test/cases/disconnected_test.rb
index c25089a420..92365351b1 100644
--- a/activerecord/test/cases/disconnected_test.rb
+++ b/activerecord/test/cases/disconnected_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class TestRecord < ActiveRecord::Base
diff --git a/activerecord/test/cases/dup_test.rb b/activerecord/test/cases/dup_test.rb
index 000ed27efb..76979dc798 100644
--- a/activerecord/test/cases/dup_test.rb
+++ b/activerecord/test/cases/dup_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/reply"
 require "models/topic"
diff --git a/activerecord/test/cases/enum_test.rb b/activerecord/test/cases/enum_test.rb
index 4ef9a125e6..8e13582f3e 100644
--- a/activerecord/test/cases/enum_test.rb
+++ b/activerecord/test/cases/enum_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/author"
 require "models/book"
diff --git a/activerecord/test/cases/errors_test.rb b/activerecord/test/cases/errors_test.rb
index e90669e0c7..45e28c4f03 100644
--- a/activerecord/test/cases/errors_test.rb
+++ b/activerecord/test/cases/errors_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class ErrorsTest < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/explain_subscriber_test.rb b/activerecord/test/cases/explain_subscriber_test.rb
index ca87e04012..0fb6bf2eed 100644
--- a/activerecord/test/cases/explain_subscriber_test.rb
+++ b/activerecord/test/cases/explain_subscriber_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "active_record/explain_subscriber"
 require "active_record/explain_registry"
diff --git a/activerecord/test/cases/explain_test.rb b/activerecord/test/cases/explain_test.rb
index 4f6bd9327c..de3ec36667 100644
--- a/activerecord/test/cases/explain_test.rb
+++ b/activerecord/test/cases/explain_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/car"
 require "active_support/core_ext/string/strip"
diff --git a/activerecord/test/cases/finder_respond_to_test.rb b/activerecord/test/cases/finder_respond_to_test.rb
index 3eaa993d45..29d7dee343 100644
--- a/activerecord/test/cases/finder_respond_to_test.rb
+++ b/activerecord/test/cases/finder_respond_to_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 
diff --git a/activerecord/test/cases/finder_test.rb b/activerecord/test/cases/finder_test.rb
index 420f552ef6..752ac519a4 100644
--- a/activerecord/test/cases/finder_test.rb
+++ b/activerecord/test/cases/finder_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/author"
diff --git a/activerecord/test/cases/fixture_set/file_test.rb b/activerecord/test/cases/fixture_set/file_test.rb
index 533edcc2e0..c7058133b2 100644
--- a/activerecord/test/cases/fixture_set/file_test.rb
+++ b/activerecord/test/cases/fixture_set/file_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "tempfile"
 
diff --git a/activerecord/test/cases/fixtures_test.rb b/activerecord/test/cases/fixtures_test.rb
index b499e60922..91d0908450 100644
--- a/activerecord/test/cases/fixtures_test.rb
+++ b/activerecord/test/cases/fixtures_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/admin"
 require "models/admin/account"
diff --git a/activerecord/test/cases/forbidden_attributes_protection_test.rb b/activerecord/test/cases/forbidden_attributes_protection_test.rb
index ffa3f63e0d..d11ec08dea 100644
--- a/activerecord/test/cases/forbidden_attributes_protection_test.rb
+++ b/activerecord/test/cases/forbidden_attributes_protection_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "active_support/core_ext/hash/indifferent_access"
 
diff --git a/activerecord/test/cases/habtm_destroy_order_test.rb b/activerecord/test/cases/habtm_destroy_order_test.rb
index 365d4576dd..124e3216d0 100644
--- a/activerecord/test/cases/habtm_destroy_order_test.rb
+++ b/activerecord/test/cases/habtm_destroy_order_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/lesson"
 require "models/student"
diff --git a/activerecord/test/cases/helper.rb b/activerecord/test/cases/helper.rb
index 5a3b8e3fb5..84a784e6d5 100644
--- a/activerecord/test/cases/helper.rb
+++ b/activerecord/test/cases/helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "config"
 
 require "stringio"
diff --git a/activerecord/test/cases/hot_compatibility_test.rb b/activerecord/test/cases/hot_compatibility_test.rb
index e107ff2362..970ccc3601 100644
--- a/activerecord/test/cases/hot_compatibility_test.rb
+++ b/activerecord/test/cases/hot_compatibility_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/connection_helper"
 
diff --git a/activerecord/test/cases/i18n_test.rb b/activerecord/test/cases/i18n_test.rb
index 7f03c5b23d..94b5e4ef2f 100644
--- a/activerecord/test/cases/i18n_test.rb
+++ b/activerecord/test/cases/i18n_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/reply"
diff --git a/activerecord/test/cases/inheritance_test.rb b/activerecord/test/cases/inheritance_test.rb
index fb5a7bcc31..e73d9d0a27 100644
--- a/activerecord/test/cases/inheritance_test.rb
+++ b/activerecord/test/cases/inheritance_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/author"
 require "models/company"
diff --git a/activerecord/test/cases/integration_test.rb b/activerecord/test/cases/integration_test.rb
index 9104976126..1075366fb1 100644
--- a/activerecord/test/cases/integration_test.rb
+++ b/activerecord/test/cases/integration_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/company"
 require "models/developer"
diff --git a/activerecord/test/cases/invalid_connection_test.rb b/activerecord/test/cases/invalid_connection_test.rb
index 1367af2859..256ad59407 100644
--- a/activerecord/test/cases/invalid_connection_test.rb
+++ b/activerecord/test/cases/invalid_connection_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 if current_adapter?(:Mysql2Adapter)
diff --git a/activerecord/test/cases/invertible_migration_test.rb b/activerecord/test/cases/invertible_migration_test.rb
index cc3951e2ba..a44a351209 100644
--- a/activerecord/test/cases/invertible_migration_test.rb
+++ b/activerecord/test/cases/invertible_migration_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class Horse < ActiveRecord::Base
diff --git a/activerecord/test/cases/json_attribute_test.rb b/activerecord/test/cases/json_attribute_test.rb
index e5848b45f8..c64e2c31de 100644
--- a/activerecord/test/cases/json_attribute_test.rb
+++ b/activerecord/test/cases/json_attribute_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "cases/json_shared_test_cases"
 
diff --git a/activerecord/test/cases/json_serialization_test.rb b/activerecord/test/cases/json_serialization_test.rb
index 9b4b61b16e..2ca95fe3b4 100644
--- a/activerecord/test/cases/json_serialization_test.rb
+++ b/activerecord/test/cases/json_serialization_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/contact"
 require "models/post"
diff --git a/activerecord/test/cases/json_shared_test_cases.rb b/activerecord/test/cases/json_shared_test_cases.rb
index 9a1c1c3f3f..1eeefb78dd 100644
--- a/activerecord/test/cases/json_shared_test_cases.rb
+++ b/activerecord/test/cases/json_shared_test_cases.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "support/schema_dumping_helper"
 
 module JSONSharedTestCases
diff --git a/activerecord/test/cases/locking_test.rb b/activerecord/test/cases/locking_test.rb
index 2fc52393f2..e67ec22c42 100644
--- a/activerecord/test/cases/locking_test.rb
+++ b/activerecord/test/cases/locking_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "thread"
 require "cases/helper"
 require "models/person"
diff --git a/activerecord/test/cases/log_subscriber_test.rb b/activerecord/test/cases/log_subscriber_test.rb
index b80257962c..0eaca0d001 100644
--- a/activerecord/test/cases/log_subscriber_test.rb
+++ b/activerecord/test/cases/log_subscriber_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/binary"
 require "models/developer"
diff --git a/activerecord/test/cases/migration/change_schema_test.rb b/activerecord/test/cases/migration/change_schema_test.rb
index 1d305fa11f..e706fc4f08 100644
--- a/activerecord/test/cases/migration/change_schema_test.rb
+++ b/activerecord/test/cases/migration/change_schema_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/change_table_test.rb b/activerecord/test/cases/migration/change_table_test.rb
index ec817a579b..f1ca91887b 100644
--- a/activerecord/test/cases/migration/change_table_test.rb
+++ b/activerecord/test/cases/migration/change_table_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/migration/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/column_attributes_test.rb b/activerecord/test/cases/migration/column_attributes_test.rb
index 48df931543..5ef0847a64 100644
--- a/activerecord/test/cases/migration/column_attributes_test.rb
+++ b/activerecord/test/cases/migration/column_attributes_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/migration/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/column_positioning_test.rb b/activerecord/test/cases/migration/column_positioning_test.rb
index f2162d91b1..bdbad431e8 100644
--- a/activerecord/test/cases/migration/column_positioning_test.rb
+++ b/activerecord/test/cases/migration/column_positioning_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/columns_test.rb b/activerecord/test/cases/migration/columns_test.rb
index 2329888345..c4751277f7 100644
--- a/activerecord/test/cases/migration/columns_test.rb
+++ b/activerecord/test/cases/migration/columns_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/migration/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/command_recorder_test.rb b/activerecord/test/cases/migration/command_recorder_test.rb
index 007926f1b9..be200a7225 100644
--- a/activerecord/test/cases/migration/command_recorder_test.rb
+++ b/activerecord/test/cases/migration/command_recorder_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/compatibility_test.rb b/activerecord/test/cases/migration/compatibility_test.rb
index 596a21dcbc..4321f967d2 100644
--- a/activerecord/test/cases/migration/compatibility_test.rb
+++ b/activerecord/test/cases/migration/compatibility_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/migration/create_join_table_test.rb b/activerecord/test/cases/migration/create_join_table_test.rb
index c4896f3d6e..0e9e880fe1 100644
--- a/activerecord/test/cases/migration/create_join_table_test.rb
+++ b/activerecord/test/cases/migration/create_join_table_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/foreign_key_test.rb b/activerecord/test/cases/migration/foreign_key_test.rb
index 7762d37915..7a44b2db75 100644
--- a/activerecord/test/cases/migration/foreign_key_test.rb
+++ b/activerecord/test/cases/migration/foreign_key_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/migration/helper.rb b/activerecord/test/cases/migration/helper.rb
index 9c0fa7339d..e366ed92b1 100644
--- a/activerecord/test/cases/migration/helper.rb
+++ b/activerecord/test/cases/migration/helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/index_test.rb b/activerecord/test/cases/migration/index_test.rb
index f10fcf1398..ccc0f4948f 100644
--- a/activerecord/test/cases/migration/index_test.rb
+++ b/activerecord/test/cases/migration/index_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/logger_test.rb b/activerecord/test/cases/migration/logger_test.rb
index 3d7c7ad469..9fe64b73a8 100644
--- a/activerecord/test/cases/migration/logger_test.rb
+++ b/activerecord/test/cases/migration/logger_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/pending_migrations_test.rb b/activerecord/test/cases/migration/pending_migrations_test.rb
index 6970fdcc87..0cb4b6cfa1 100644
--- a/activerecord/test/cases/migration/pending_migrations_test.rb
+++ b/activerecord/test/cases/migration/pending_migrations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/references_foreign_key_test.rb b/activerecord/test/cases/migration/references_foreign_key_test.rb
index 718b9a0613..405fd7aaed 100644
--- a/activerecord/test/cases/migration/references_foreign_key_test.rb
+++ b/activerecord/test/cases/migration/references_foreign_key_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 if ActiveRecord::Base.connection.supports_foreign_keys_in_create?
diff --git a/activerecord/test/cases/migration/references_index_test.rb b/activerecord/test/cases/migration/references_index_test.rb
index 2866cabab6..2954f1e275 100644
--- a/activerecord/test/cases/migration/references_index_test.rb
+++ b/activerecord/test/cases/migration/references_index_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/references_statements_test.rb b/activerecord/test/cases/migration/references_statements_test.rb
index e9eb9968cb..f8b373bdee 100644
--- a/activerecord/test/cases/migration/references_statements_test.rb
+++ b/activerecord/test/cases/migration/references_statements_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/migration/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration/rename_table_test.rb b/activerecord/test/cases/migration/rename_table_test.rb
index 5da3ad33a3..bee528ca8a 100644
--- a/activerecord/test/cases/migration/rename_table_test.rb
+++ b/activerecord/test/cases/migration/rename_table_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/migration/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/migration_test.rb b/activerecord/test/cases/migration_test.rb
index 3a49a41580..315e58668a 100644
--- a/activerecord/test/cases/migration_test.rb
+++ b/activerecord/test/cases/migration_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "cases/migration/helper"
 require "bigdecimal/util"
diff --git a/activerecord/test/cases/migrator_test.rb b/activerecord/test/cases/migrator_test.rb
index 2e4b454a86..b93643922d 100644
--- a/activerecord/test/cases/migrator_test.rb
+++ b/activerecord/test/cases/migrator_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "cases/migration/helper"
 
diff --git a/activerecord/test/cases/mixin_test.rb b/activerecord/test/cases/mixin_test.rb
index a8af8e30f7..82190c283e 100644
--- a/activerecord/test/cases/mixin_test.rb
+++ b/activerecord/test/cases/mixin_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class Mixin < ActiveRecord::Base
diff --git a/activerecord/test/cases/modules_test.rb b/activerecord/test/cases/modules_test.rb
index f8a7bab35f..514911cb13 100644
--- a/activerecord/test/cases/modules_test.rb
+++ b/activerecord/test/cases/modules_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/company_in_module"
 require "models/shop"
diff --git a/activerecord/test/cases/multiparameter_attributes_test.rb b/activerecord/test/cases/multiparameter_attributes_test.rb
index ceb5724377..7a35b5dc84 100644
--- a/activerecord/test/cases/multiparameter_attributes_test.rb
+++ b/activerecord/test/cases/multiparameter_attributes_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/customer"
diff --git a/activerecord/test/cases/multiple_db_test.rb b/activerecord/test/cases/multiple_db_test.rb
index e3bb51bd77..bfa5da765b 100644
--- a/activerecord/test/cases/multiple_db_test.rb
+++ b/activerecord/test/cases/multiple_db_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/entrant"
 require "models/bird"
diff --git a/activerecord/test/cases/nested_attributes_test.rb b/activerecord/test/cases/nested_attributes_test.rb
index 154faa56aa..aea65a7baf 100644
--- a/activerecord/test/cases/nested_attributes_test.rb
+++ b/activerecord/test/cases/nested_attributes_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/pirate"
 require "models/ship"
diff --git a/activerecord/test/cases/nested_attributes_with_callbacks_test.rb b/activerecord/test/cases/nested_attributes_with_callbacks_test.rb
index b9d2acbed2..905ddef063 100644
--- a/activerecord/test/cases/nested_attributes_with_callbacks_test.rb
+++ b/activerecord/test/cases/nested_attributes_with_callbacks_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/pirate"
 require "models/bird"
diff --git a/activerecord/test/cases/numeric_data_test.rb b/activerecord/test/cases/numeric_data_test.rb
index 76b97033af..b0a3d566bb 100644
--- a/activerecord/test/cases/numeric_data_test.rb
+++ b/activerecord/test/cases/numeric_data_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/numeric_data"
 
diff --git a/activerecord/test/cases/persistence_test.rb b/activerecord/test/cases/persistence_test.rb
index 5895c51714..8f0099ee48 100644
--- a/activerecord/test/cases/persistence_test.rb
+++ b/activerecord/test/cases/persistence_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/aircraft"
 require "models/post"
diff --git a/activerecord/test/cases/pooled_connections_test.rb b/activerecord/test/cases/pooled_connections_test.rb
index f1b0d08765..d99318f1aa 100644
--- a/activerecord/test/cases/pooled_connections_test.rb
+++ b/activerecord/test/cases/pooled_connections_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/project"
 require "timeout"
diff --git a/activerecord/test/cases/primary_keys_test.rb b/activerecord/test/cases/primary_keys_test.rb
index 56229b70bc..61cd6b45a1 100644
--- a/activerecord/test/cases/primary_keys_test.rb
+++ b/activerecord/test/cases/primary_keys_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 require "models/topic"
diff --git a/activerecord/test/cases/query_cache_test.rb b/activerecord/test/cases/query_cache_test.rb
index b018a7b6c0..fb5305d288 100644
--- a/activerecord/test/cases/query_cache_test.rb
+++ b/activerecord/test/cases/query_cache_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/task"
diff --git a/activerecord/test/cases/quoting_test.rb b/activerecord/test/cases/quoting_test.rb
index 0819776fbf..4cfad9c21f 100644
--- a/activerecord/test/cases/quoting_test.rb
+++ b/activerecord/test/cases/quoting_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/readonly_test.rb b/activerecord/test/cases/readonly_test.rb
index 24b678310d..2e8d108985 100644
--- a/activerecord/test/cases/readonly_test.rb
+++ b/activerecord/test/cases/readonly_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/author"
 require "models/post"
diff --git a/activerecord/test/cases/reaper_test.rb b/activerecord/test/cases/reaper_test.rb
index 249878b67d..153311bece 100644
--- a/activerecord/test/cases/reaper_test.rb
+++ b/activerecord/test/cases/reaper_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/reflection_test.rb b/activerecord/test/cases/reflection_test.rb
index c1c2efb9c8..e27000472c 100644
--- a/activerecord/test/cases/reflection_test.rb
+++ b/activerecord/test/cases/reflection_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/customer"
diff --git a/activerecord/test/cases/relation/delegation_test.rb b/activerecord/test/cases/relation/delegation_test.rb
index 3b15f051b2..5945eab75a 100644
--- a/activerecord/test/cases/relation/delegation_test.rb
+++ b/activerecord/test/cases/relation/delegation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/comment"
diff --git a/activerecord/test/cases/relation/merging_test.rb b/activerecord/test/cases/relation/merging_test.rb
index 3901824aac..feb5604284 100644
--- a/activerecord/test/cases/relation/merging_test.rb
+++ b/activerecord/test/cases/relation/merging_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/author"
 require "models/comment"
diff --git a/activerecord/test/cases/relation/mutation_test.rb b/activerecord/test/cases/relation/mutation_test.rb
index dea787c07f..113ddaa780 100644
--- a/activerecord/test/cases/relation/mutation_test.rb
+++ b/activerecord/test/cases/relation/mutation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 
diff --git a/activerecord/test/cases/relation/or_test.rb b/activerecord/test/cases/relation/or_test.rb
index 61b6601580..541feabeb6 100644
--- a/activerecord/test/cases/relation/or_test.rb
+++ b/activerecord/test/cases/relation/or_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 
diff --git a/activerecord/test/cases/relation/predicate_builder_test.rb b/activerecord/test/cases/relation/predicate_builder_test.rb
index 48758dc148..94cd704a14 100644
--- a/activerecord/test/cases/relation/predicate_builder_test.rb
+++ b/activerecord/test/cases/relation/predicate_builder_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 
diff --git a/activerecord/test/cases/relation/record_fetch_warning_test.rb b/activerecord/test/cases/relation/record_fetch_warning_test.rb
index 62ca051431..59eb524f5a 100644
--- a/activerecord/test/cases/relation/record_fetch_warning_test.rb
+++ b/activerecord/test/cases/relation/record_fetch_warning_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "active_record/relation/record_fetch_warning"
diff --git a/activerecord/test/cases/relation/where_chain_test.rb b/activerecord/test/cases/relation/where_chain_test.rb
index 86e150ed79..351e955947 100644
--- a/activerecord/test/cases/relation/where_chain_test.rb
+++ b/activerecord/test/cases/relation/where_chain_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/comment"
diff --git a/activerecord/test/cases/relation/where_clause_test.rb b/activerecord/test/cases/relation/where_clause_test.rb
index f8eb0dee91..59a7002774 100644
--- a/activerecord/test/cases/relation/where_clause_test.rb
+++ b/activerecord/test/cases/relation/where_clause_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class ActiveRecord::Relation
diff --git a/activerecord/test/cases/relation/where_test.rb b/activerecord/test/cases/relation/where_test.rb
index 42dae4d569..ac4fcfff1d 100644
--- a/activerecord/test/cases/relation/where_test.rb
+++ b/activerecord/test/cases/relation/where_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/author"
 require "models/binary"
diff --git a/activerecord/test/cases/relation_test.rb b/activerecord/test/cases/relation_test.rb
index a403824f1a..f81b155657 100644
--- a/activerecord/test/cases/relation_test.rb
+++ b/activerecord/test/cases/relation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/comment"
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 5767dec315..c804bbf3a5 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/tag"
 require "models/tagging"
diff --git a/activerecord/test/cases/reload_models_test.rb b/activerecord/test/cases/reload_models_test.rb
index 3f4c0c03e3..6c2f9fb5ab 100644
--- a/activerecord/test/cases/reload_models_test.rb
+++ b/activerecord/test/cases/reload_models_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/owner"
 require "models/pet"
diff --git a/activerecord/test/cases/reserved_word_test.rb b/activerecord/test/cases/reserved_word_test.rb
index f3019a5326..44f7a28215 100644
--- a/activerecord/test/cases/reserved_word_test.rb
+++ b/activerecord/test/cases/reserved_word_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class ReservedWordTest < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/result_test.rb b/activerecord/test/cases/result_test.rb
index 1a0b7c6ca7..b4044acd57 100644
--- a/activerecord/test/cases/result_test.rb
+++ b/activerecord/test/cases/result_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/sanitize_test.rb b/activerecord/test/cases/sanitize_test.rb
index 72f09186e2..a0e7f4ae60 100644
--- a/activerecord/test/cases/sanitize_test.rb
+++ b/activerecord/test/cases/sanitize_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/binary"
 require "models/author"
diff --git a/activerecord/test/cases/schema_dumper_test.rb b/activerecord/test/cases/schema_dumper_test.rb
index 4c81e825fa..86a0e93832 100644
--- a/activerecord/test/cases/schema_dumper_test.rb
+++ b/activerecord/test/cases/schema_dumper_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/schema_loading_test.rb b/activerecord/test/cases/schema_loading_test.rb
index 362370ac61..e3b7755f07 100644
--- a/activerecord/test/cases/schema_loading_test.rb
+++ b/activerecord/test/cases/schema_loading_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module SchemaLoadCounter
diff --git a/activerecord/test/cases/scoping/default_scoping_test.rb b/activerecord/test/cases/scoping/default_scoping_test.rb
index 89fb434b27..9919ed5e3f 100644
--- a/activerecord/test/cases/scoping/default_scoping_test.rb
+++ b/activerecord/test/cases/scoping/default_scoping_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/comment"
diff --git a/activerecord/test/cases/scoping/named_scoping_test.rb b/activerecord/test/cases/scoping/named_scoping_test.rb
index 483ea7128d..ea338a9847 100644
--- a/activerecord/test/cases/scoping/named_scoping_test.rb
+++ b/activerecord/test/cases/scoping/named_scoping_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/topic"
diff --git a/activerecord/test/cases/scoping/relation_scoping_test.rb b/activerecord/test/cases/scoping/relation_scoping_test.rb
index 10553bf057..644e7eb692 100644
--- a/activerecord/test/cases/scoping/relation_scoping_test.rb
+++ b/activerecord/test/cases/scoping/relation_scoping_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/post"
 require "models/author"
diff --git a/activerecord/test/cases/secure_token_test.rb b/activerecord/test/cases/secure_token_test.rb
index 7b9cbee40a..987ae3074f 100644
--- a/activerecord/test/cases/secure_token_test.rb
+++ b/activerecord/test/cases/secure_token_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/user"
 
diff --git a/activerecord/test/cases/serialization_test.rb b/activerecord/test/cases/serialization_test.rb
index ec33ad38f2..82e0311d84 100644
--- a/activerecord/test/cases/serialization_test.rb
+++ b/activerecord/test/cases/serialization_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/contact"
 require "models/topic"
diff --git a/activerecord/test/cases/serialized_attribute_test.rb b/activerecord/test/cases/serialized_attribute_test.rb
index e1bdaab5cf..6525730350 100644
--- a/activerecord/test/cases/serialized_attribute_test.rb
+++ b/activerecord/test/cases/serialized_attribute_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/reply"
diff --git a/activerecord/test/cases/statement_cache_test.rb b/activerecord/test/cases/statement_cache_test.rb
index fab3648564..ee1a8bfc36 100644
--- a/activerecord/test/cases/statement_cache_test.rb
+++ b/activerecord/test/cases/statement_cache_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/book"
 require "models/liquid"
diff --git a/activerecord/test/cases/store_test.rb b/activerecord/test/cases/store_test.rb
index 633a8a0ebc..0ece0632fe 100644
--- a/activerecord/test/cases/store_test.rb
+++ b/activerecord/test/cases/store_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/admin"
 require "models/admin/user"
diff --git a/activerecord/test/cases/suppressor_test.rb b/activerecord/test/cases/suppressor_test.rb
index a7d16b7cdb..bc85461322 100644
--- a/activerecord/test/cases/suppressor_test.rb
+++ b/activerecord/test/cases/suppressor_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/notification"
 require "models/user"
diff --git a/activerecord/test/cases/tasks/database_tasks_test.rb b/activerecord/test/cases/tasks/database_tasks_test.rb
index c47c97e9d9..b8280c4aaf 100644
--- a/activerecord/test/cases/tasks/database_tasks_test.rb
+++ b/activerecord/test/cases/tasks/database_tasks_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "active_record/tasks/database_tasks"
 
diff --git a/activerecord/test/cases/tasks/mysql_rake_test.rb b/activerecord/test/cases/tasks/mysql_rake_test.rb
index 9c6fb14376..02c0cfbb92 100644
--- a/activerecord/test/cases/tasks/mysql_rake_test.rb
+++ b/activerecord/test/cases/tasks/mysql_rake_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "active_record/tasks/database_tasks"
 
diff --git a/activerecord/test/cases/tasks/postgresql_rake_test.rb b/activerecord/test/cases/tasks/postgresql_rake_test.rb
index a2e968aedf..9369d1eedb 100644
--- a/activerecord/test/cases/tasks/postgresql_rake_test.rb
+++ b/activerecord/test/cases/tasks/postgresql_rake_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "active_record/tasks/database_tasks"
 
diff --git a/activerecord/test/cases/tasks/sqlite_rake_test.rb b/activerecord/test/cases/tasks/sqlite_rake_test.rb
index ccb3834fee..0deedad671 100644
--- a/activerecord/test/cases/tasks/sqlite_rake_test.rb
+++ b/activerecord/test/cases/tasks/sqlite_rake_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "active_record/tasks/database_tasks"
 require "pathname"
diff --git a/activerecord/test/cases/test_case.rb b/activerecord/test/cases/test_case.rb
index 9f594fef85..247d0ec3d1 100644
--- a/activerecord/test/cases/test_case.rb
+++ b/activerecord/test/cases/test_case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "active_support/test_case"
 require "active_support/testing/autorun"
 require "active_support/testing/method_call_assertions"
diff --git a/activerecord/test/cases/test_fixtures_test.rb b/activerecord/test/cases/test_fixtures_test.rb
index 58d3bea3a2..e542716563 100644
--- a/activerecord/test/cases/test_fixtures_test.rb
+++ b/activerecord/test/cases/test_fixtures_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class TestFixturesTest < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/time_precision_test.rb b/activerecord/test/cases/time_precision_test.rb
index 09c585167e..3a8f8af0e6 100644
--- a/activerecord/test/cases/time_precision_test.rb
+++ b/activerecord/test/cases/time_precision_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/schema_dumping_helper"
 
diff --git a/activerecord/test/cases/timestamp_test.rb b/activerecord/test/cases/timestamp_test.rb
index 39b40e3411..0f58c96504 100644
--- a/activerecord/test/cases/timestamp_test.rb
+++ b/activerecord/test/cases/timestamp_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "support/ddl_helper"
 require "models/developer"
diff --git a/activerecord/test/cases/touch_later_test.rb b/activerecord/test/cases/touch_later_test.rb
index d1e8c649d9..24b5e8886f 100644
--- a/activerecord/test/cases/touch_later_test.rb
+++ b/activerecord/test/cases/touch_later_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/invoice"
 require "models/line_item"
diff --git a/activerecord/test/cases/transaction_callbacks_test.rb b/activerecord/test/cases/transaction_callbacks_test.rb
index eaa4dd09a9..aa0d8f5e65 100644
--- a/activerecord/test/cases/transaction_callbacks_test.rb
+++ b/activerecord/test/cases/transaction_callbacks_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/owner"
 require "models/pet"
diff --git a/activerecord/test/cases/transaction_isolation_test.rb b/activerecord/test/cases/transaction_isolation_test.rb
index 58abfadaf4..380d7dbb0a 100644
--- a/activerecord/test/cases/transaction_isolation_test.rb
+++ b/activerecord/test/cases/transaction_isolation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 unless ActiveRecord::Base.connection.supports_transaction_isolation?
diff --git a/activerecord/test/cases/transactions_test.rb b/activerecord/test/cases/transactions_test.rb
index 79ba306ef5..ced6045955 100644
--- a/activerecord/test/cases/transactions_test.rb
+++ b/activerecord/test/cases/transactions_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/reply"
diff --git a/activerecord/test/cases/type/adapter_specific_registry_test.rb b/activerecord/test/cases/type/adapter_specific_registry_test.rb
index 8b836b4793..a723a952ea 100644
--- a/activerecord/test/cases/type/adapter_specific_registry_test.rb
+++ b/activerecord/test/cases/type/adapter_specific_registry_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/type/date_time_test.rb b/activerecord/test/cases/type/date_time_test.rb
index 6848619ece..9307587564 100644
--- a/activerecord/test/cases/type/date_time_test.rb
+++ b/activerecord/test/cases/type/date_time_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/task"
 
diff --git a/activerecord/test/cases/type/integer_test.rb b/activerecord/test/cases/type/integer_test.rb
index 368b6d7199..13d6d2093b 100644
--- a/activerecord/test/cases/type/integer_test.rb
+++ b/activerecord/test/cases/type/integer_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/company"
 
diff --git a/activerecord/test/cases/type/string_test.rb b/activerecord/test/cases/type/string_test.rb
index a95da864fa..899d7ae767 100644
--- a/activerecord/test/cases/type/string_test.rb
+++ b/activerecord/test/cases/type/string_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/type/type_map_test.rb b/activerecord/test/cases/type/type_map_test.rb
index 2959d36466..f171175b2a 100644
--- a/activerecord/test/cases/type/type_map_test.rb
+++ b/activerecord/test/cases/type/type_map_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/type/unsigned_integer_test.rb b/activerecord/test/cases/type/unsigned_integer_test.rb
index 1cd4dbc2c5..b0a60a2b3d 100644
--- a/activerecord/test/cases/type/unsigned_integer_test.rb
+++ b/activerecord/test/cases/type/unsigned_integer_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/type_test.rb b/activerecord/test/cases/type_test.rb
index d45a9b3141..0f9f698760 100644
--- a/activerecord/test/cases/type_test.rb
+++ b/activerecord/test/cases/type_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class TypeTest < ActiveRecord::TestCase
diff --git a/activerecord/test/cases/types_test.rb b/activerecord/test/cases/types_test.rb
index 11476ea0ef..ea55bb00cd 100644
--- a/activerecord/test/cases/types_test.rb
+++ b/activerecord/test/cases/types_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 module ActiveRecord
diff --git a/activerecord/test/cases/unconnected_test.rb b/activerecord/test/cases/unconnected_test.rb
index b210584644..30efd03955 100644
--- a/activerecord/test/cases/unconnected_test.rb
+++ b/activerecord/test/cases/unconnected_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 
 class TestRecord < ActiveRecord::Base
diff --git a/activerecord/test/cases/validations/absence_validation_test.rb b/activerecord/test/cases/validations/absence_validation_test.rb
index 870619e4e7..051f14dbb7 100644
--- a/activerecord/test/cases/validations/absence_validation_test.rb
+++ b/activerecord/test/cases/validations/absence_validation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/face"
 require "models/interest"
diff --git a/activerecord/test/cases/validations/association_validation_test.rb b/activerecord/test/cases/validations/association_validation_test.rb
index f5ceb27d97..0935dc8c32 100644
--- a/activerecord/test/cases/validations/association_validation_test.rb
+++ b/activerecord/test/cases/validations/association_validation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/reply"
diff --git a/activerecord/test/cases/validations/i18n_generate_message_validation_test.rb b/activerecord/test/cases/validations/i18n_generate_message_validation_test.rb
index a57065ba75..fdfd568897 100644
--- a/activerecord/test/cases/validations/i18n_generate_message_validation_test.rb
+++ b/activerecord/test/cases/validations/i18n_generate_message_validation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 
diff --git a/activerecord/test/cases/validations/i18n_validation_test.rb b/activerecord/test/cases/validations/i18n_validation_test.rb
index fd88a3ea67..a020c877e7 100644
--- a/activerecord/test/cases/validations/i18n_validation_test.rb
+++ b/activerecord/test/cases/validations/i18n_validation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/reply"
diff --git a/activerecord/test/cases/validations/length_validation_test.rb b/activerecord/test/cases/validations/length_validation_test.rb
index ba45c6dcc1..7f840dfa7c 100644
--- a/activerecord/test/cases/validations/length_validation_test.rb
+++ b/activerecord/test/cases/validations/length_validation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 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 13956e26ec..dee8528124 100644
--- a/activerecord/test/cases/validations/presence_validation_test.rb
+++ b/activerecord/test/cases/validations/presence_validation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 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 28605d2f8e..e943d03720 100644
--- a/activerecord/test/cases/validations/uniqueness_validation_test.rb
+++ b/activerecord/test/cases/validations/uniqueness_validation_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/reply"
diff --git a/activerecord/test/cases/validations_repair_helper.rb b/activerecord/test/cases/validations_repair_helper.rb
index b30666d876..30299fd2c6 100644
--- a/activerecord/test/cases/validations_repair_helper.rb
+++ b/activerecord/test/cases/validations_repair_helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module ActiveRecord
   module ValidationsRepairHelper
     extend ActiveSupport::Concern
diff --git a/activerecord/test/cases/validations_test.rb b/activerecord/test/cases/validations_test.rb
index a305aa295a..fc9678211a 100644
--- a/activerecord/test/cases/validations_test.rb
+++ b/activerecord/test/cases/validations_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/reply"
diff --git a/activerecord/test/cases/view_test.rb b/activerecord/test/cases/view_test.rb
index 1d21a2454f..89b72ec336 100644
--- a/activerecord/test/cases/view_test.rb
+++ b/activerecord/test/cases/view_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/book"
 require "support/schema_dumping_helper"
diff --git a/activerecord/test/cases/yaml_serialization_test.rb b/activerecord/test/cases/yaml_serialization_test.rb
index dd8d2c1178..1b67e150f3 100644
--- a/activerecord/test/cases/yaml_serialization_test.rb
+++ b/activerecord/test/cases/yaml_serialization_test.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require "cases/helper"
 require "models/topic"
 require "models/reply"