From c2bc569d2d538584cfc081e5775de17cdf2f054b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafael=20Mendon=C3=A7a=20Fran=C3=A7a?=
 <rafaelmfranca@gmail.com>
Date: Mon, 13 Feb 2017 15:58:58 -0300
Subject: Enable frozen_string_literal in all files in arel

---
 .rubocop.yml                                 | 6 ++++++
 Gemfile                                      | 1 +
 Rakefile                                     | 1 +
 arel.gemspec                                 | 1 +
 arel.gemspec.erb                             | 1 +
 lib/arel.rb                                  | 1 +
 lib/arel/alias_predication.rb                | 1 +
 lib/arel/attributes.rb                       | 1 +
 lib/arel/attributes/attribute.rb             | 1 +
 lib/arel/collectors/bind.rb                  | 1 +
 lib/arel/collectors/plain_string.rb          | 3 ++-
 lib/arel/collectors/sql_string.rb            | 1 +
 lib/arel/compatibility/wheres.rb             | 1 +
 lib/arel/crud.rb                             | 1 +
 lib/arel/delete_manager.rb                   | 1 +
 lib/arel/errors.rb                           | 1 +
 lib/arel/expressions.rb                      | 1 +
 lib/arel/factory_methods.rb                  | 1 +
 lib/arel/insert_manager.rb                   | 1 +
 lib/arel/math.rb                             | 1 +
 lib/arel/nodes.rb                            | 1 +
 lib/arel/nodes/and.rb                        | 1 +
 lib/arel/nodes/ascending.rb                  | 1 +
 lib/arel/nodes/binary.rb                     | 1 +
 lib/arel/nodes/bind_param.rb                 | 1 +
 lib/arel/nodes/case.rb                       | 1 +
 lib/arel/nodes/casted.rb                     | 1 +
 lib/arel/nodes/count.rb                      | 1 +
 lib/arel/nodes/delete_statement.rb           | 1 +
 lib/arel/nodes/descending.rb                 | 1 +
 lib/arel/nodes/equality.rb                   | 1 +
 lib/arel/nodes/extract.rb                    | 1 +
 lib/arel/nodes/false.rb                      | 1 +
 lib/arel/nodes/full_outer_join.rb            | 1 +
 lib/arel/nodes/function.rb                   | 1 +
 lib/arel/nodes/grouping.rb                   | 1 +
 lib/arel/nodes/in.rb                         | 1 +
 lib/arel/nodes/infix_operation.rb            | 1 +
 lib/arel/nodes/inner_join.rb                 | 1 +
 lib/arel/nodes/insert_statement.rb           | 1 +
 lib/arel/nodes/join_source.rb                | 1 +
 lib/arel/nodes/matches.rb                    | 1 +
 lib/arel/nodes/named_function.rb             | 1 +
 lib/arel/nodes/node.rb                       | 1 +
 lib/arel/nodes/outer_join.rb                 | 1 +
 lib/arel/nodes/over.rb                       | 1 +
 lib/arel/nodes/regexp.rb                     | 1 +
 lib/arel/nodes/right_outer_join.rb           | 1 +
 lib/arel/nodes/select_core.rb                | 1 +
 lib/arel/nodes/select_statement.rb           | 1 +
 lib/arel/nodes/sql_literal.rb                | 1 +
 lib/arel/nodes/string_join.rb                | 1 +
 lib/arel/nodes/table_alias.rb                | 1 +
 lib/arel/nodes/terminal.rb                   | 1 +
 lib/arel/nodes/true.rb                       | 1 +
 lib/arel/nodes/unary.rb                      | 1 +
 lib/arel/nodes/unary_operation.rb            | 1 +
 lib/arel/nodes/unqualified_column.rb         | 1 +
 lib/arel/nodes/update_statement.rb           | 1 +
 lib/arel/nodes/values.rb                     | 1 +
 lib/arel/nodes/window.rb                     | 1 +
 lib/arel/nodes/with.rb                       | 1 +
 lib/arel/order_predications.rb               | 1 +
 lib/arel/predications.rb                     | 1 +
 lib/arel/select_manager.rb                   | 1 +
 lib/arel/table.rb                            | 1 +
 lib/arel/tree_manager.rb                     | 1 +
 lib/arel/update_manager.rb                   | 1 +
 lib/arel/visitors.rb                         | 1 +
 lib/arel/visitors/bind_substitute.rb         | 1 +
 lib/arel/visitors/depth_first.rb             | 1 +
 lib/arel/visitors/reduce.rb                  | 1 +
 lib/arel/visitors/visitor.rb                 | 1 +
 lib/arel/window_predications.rb              | 1 +
 test/attributes/test_attribute.rb            | 1 +
 test/collectors/test_bind_collector.rb       | 1 +
 test/collectors/test_sql_string.rb           | 1 +
 test/helper.rb                               | 1 +
 test/nodes/test_and.rb                       | 1 +
 test/nodes/test_as.rb                        | 1 +
 test/nodes/test_ascending.rb                 | 1 +
 test/nodes/test_bin.rb                       | 1 +
 test/nodes/test_binary.rb                    | 1 +
 test/nodes/test_bind_param.rb                | 1 +
 test/nodes/test_case.rb                      | 1 +
 test/nodes/test_casted.rb                    | 1 +
 test/nodes/test_count.rb                     | 1 +
 test/nodes/test_delete_statement.rb          | 1 +
 test/nodes/test_descending.rb                | 1 +
 test/nodes/test_distinct.rb                  | 1 +
 test/nodes/test_equality.rb                  | 1 +
 test/nodes/test_extract.rb                   | 1 +
 test/nodes/test_false.rb                     | 1 +
 test/nodes/test_grouping.rb                  | 1 +
 test/nodes/test_infix_operation.rb           | 1 +
 test/nodes/test_insert_statement.rb          | 1 +
 test/nodes/test_named_function.rb            | 1 +
 test/nodes/test_node.rb                      | 1 +
 test/nodes/test_not.rb                       | 1 +
 test/nodes/test_or.rb                        | 1 +
 test/nodes/test_over.rb                      | 1 +
 test/nodes/test_select_core.rb               | 1 +
 test/nodes/test_select_statement.rb          | 1 +
 test/nodes/test_sql_literal.rb               | 1 +
 test/nodes/test_sum.rb                       | 1 +
 test/nodes/test_table_alias.rb               | 1 +
 test/nodes/test_true.rb                      | 1 +
 test/nodes/test_unary_operation.rb           | 1 +
 test/nodes/test_update_statement.rb          | 1 +
 test/nodes/test_window.rb                    | 1 +
 test/support/fake_record.rb                  | 1 +
 test/test_attributes.rb                      | 1 +
 test/test_crud.rb                            | 1 +
 test/test_delete_manager.rb                  | 1 +
 test/test_factory_methods.rb                 | 1 +
 test/test_insert_manager.rb                  | 1 +
 test/test_select_manager.rb                  | 1 +
 test/test_table.rb                           | 1 +
 test/test_update_manager.rb                  | 1 +
 test/visitors/test_bind_visitor.rb           | 1 +
 test/visitors/test_depth_first.rb            | 1 +
 test/visitors/test_dispatch_contamination.rb | 1 +
 test/visitors/test_dot.rb                    | 1 +
 test/visitors/test_ibm_db.rb                 | 1 +
 test/visitors/test_informix.rb               | 1 +
 test/visitors/test_mssql.rb                  | 1 +
 test/visitors/test_mysql.rb                  | 1 +
 test/visitors/test_oracle.rb                 | 1 +
 test/visitors/test_oracle12.rb               | 1 +
 test/visitors/test_postgres.rb               | 1 +
 test/visitors/test_sqlite.rb                 | 1 +
 test/visitors/test_to_sql.rb                 | 1 +
 132 files changed, 138 insertions(+), 1 deletion(-)
 create mode 100644 .rubocop.yml

diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000000..2379a2afd0
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,6 @@
+AllCops:
+  DisabledByDefault: true
+
+Style/FrozenStringLiteralComment:
+  Enabled: true
+  EnforcedStyle: always
diff --git a/Gemfile b/Gemfile
index 07483b27d3..3b791743de 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 source "https://rubygems.org/"
 
 gemspec
diff --git a/Rakefile b/Rakefile
index 02b92e0b44..2625ee9506 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'bundler'
 Bundler::GemHelper.install_tasks
 
diff --git a/arel.gemspec b/arel.gemspec
index 68b5a72101..9cbf991ab7 100644
--- a/arel.gemspec
+++ b/arel.gemspec
@@ -1,4 +1,5 @@
 # # -*- encoding: utf-8 -*-
+# frozen_string_literal: true
 $:.push File.expand_path("../lib", __FILE__)
 require "arel"
 
diff --git a/arel.gemspec.erb b/arel.gemspec.erb
index a64e585a28..f7ff99469c 100644
--- a/arel.gemspec.erb
+++ b/arel.gemspec.erb
@@ -1,4 +1,5 @@
 # # -*- encoding: utf-8 -*-
+# frozen_string_literal: true
 $:.push File.expand_path("../lib", __FILE__)
 require "arel"
 
diff --git a/lib/arel.rb b/lib/arel.rb
index 710914a2e3..f0d2bdce78 100644
--- a/lib/arel.rb
+++ b/lib/arel.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'arel/errors'
 
 require 'arel/crud'
diff --git a/lib/arel/alias_predication.rb b/lib/arel/alias_predication.rb
index f42e9ee1a6..cb50fb95be 100644
--- a/lib/arel/alias_predication.rb
+++ b/lib/arel/alias_predication.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module AliasPredication
     def as other
diff --git a/lib/arel/attributes.rb b/lib/arel/attributes.rb
index 92cc041f83..ed4739ebed 100644
--- a/lib/arel/attributes.rb
+++ b/lib/arel/attributes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'arel/attributes/attribute'
 
 module Arel
diff --git a/lib/arel/attributes/attribute.rb b/lib/arel/attributes/attribute.rb
index cda5a5a3db..41bc0c32c7 100644
--- a/lib/arel/attributes/attribute.rb
+++ b/lib/arel/attributes/attribute.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Attributes
     class Attribute < Struct.new :relation, :name
diff --git a/lib/arel/collectors/bind.rb b/lib/arel/collectors/bind.rb
index 05cd966509..dfa79d1001 100644
--- a/lib/arel/collectors/bind.rb
+++ b/lib/arel/collectors/bind.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Collectors
     class Bind
diff --git a/lib/arel/collectors/plain_string.rb b/lib/arel/collectors/plain_string.rb
index 2505bc376e..1e8d2a2152 100644
--- a/lib/arel/collectors/plain_string.rb
+++ b/lib/arel/collectors/plain_string.rb
@@ -1,8 +1,9 @@
+# frozen_string_literal: true
 module Arel
   module Collectors
     class PlainString
       def initialize
-        @str = ''
+        @str = ''.dup
       end
 
       def value
diff --git a/lib/arel/collectors/sql_string.rb b/lib/arel/collectors/sql_string.rb
index fd2faaef3a..5f42117331 100644
--- a/lib/arel/collectors/sql_string.rb
+++ b/lib/arel/collectors/sql_string.rb
@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: true
 
 require 'arel/collectors/plain_string'
 
diff --git a/lib/arel/compatibility/wheres.rb b/lib/arel/compatibility/wheres.rb
index b73b178651..3e60894bd8 100644
--- a/lib/arel/compatibility/wheres.rb
+++ b/lib/arel/compatibility/wheres.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Compatibility # :nodoc:
     class Wheres # :nodoc:
diff --git a/lib/arel/crud.rb b/lib/arel/crud.rb
index d310c7381f..2d10432205 100644
--- a/lib/arel/crud.rb
+++ b/lib/arel/crud.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   ###
   # FIXME hopefully we can remove this
diff --git a/lib/arel/delete_manager.rb b/lib/arel/delete_manager.rb
index 20e988e01f..aee4511249 100644
--- a/lib/arel/delete_manager.rb
+++ b/lib/arel/delete_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   class DeleteManager < Arel::TreeManager
     def initialize
diff --git a/lib/arel/errors.rb b/lib/arel/errors.rb
index c8a6af9f77..86fbb80461 100644
--- a/lib/arel/errors.rb
+++ b/lib/arel/errors.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   class ArelError < StandardError
   end
diff --git a/lib/arel/expressions.rb b/lib/arel/expressions.rb
index d40268c292..612a0942f1 100644
--- a/lib/arel/expressions.rb
+++ b/lib/arel/expressions.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Expressions
     def count distinct = false
diff --git a/lib/arel/factory_methods.rb b/lib/arel/factory_methods.rb
index cb66f6f888..6647c5ac44 100644
--- a/lib/arel/factory_methods.rb
+++ b/lib/arel/factory_methods.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   ###
   # Methods for creating various nodes
diff --git a/lib/arel/insert_manager.rb b/lib/arel/insert_manager.rb
index 7829c3f4f9..d0a49842de 100644
--- a/lib/arel/insert_manager.rb
+++ b/lib/arel/insert_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   class InsertManager < Arel::TreeManager
     def initialize
diff --git a/lib/arel/math.rb b/lib/arel/math.rb
index 04cae84598..9e6549b58f 100644
--- a/lib/arel/math.rb
+++ b/lib/arel/math.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Math
     def *(other)
diff --git a/lib/arel/nodes.rb b/lib/arel/nodes.rb
index ff27bb9aa8..8c9815a96b 100644
--- a/lib/arel/nodes.rb
+++ b/lib/arel/nodes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 # node
 require 'arel/nodes/node'
 require 'arel/nodes/select_statement'
diff --git a/lib/arel/nodes/and.rb b/lib/arel/nodes/and.rb
index 8e1afda709..1e2f61cf43 100644
--- a/lib/arel/nodes/and.rb
+++ b/lib/arel/nodes/and.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class And < Arel::Nodes::Node
diff --git a/lib/arel/nodes/ascending.rb b/lib/arel/nodes/ascending.rb
index bca00a8339..adadab55e4 100644
--- a/lib/arel/nodes/ascending.rb
+++ b/lib/arel/nodes/ascending.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Ascending < Ordering
diff --git a/lib/arel/nodes/binary.rb b/lib/arel/nodes/binary.rb
index 763091c267..3001788774 100644
--- a/lib/arel/nodes/binary.rb
+++ b/lib/arel/nodes/binary.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Binary < Arel::Nodes::Node
diff --git a/lib/arel/nodes/bind_param.rb b/lib/arel/nodes/bind_param.rb
index 3a4aedc4ba..9e297831cd 100644
--- a/lib/arel/nodes/bind_param.rb
+++ b/lib/arel/nodes/bind_param.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class BindParam < Node
diff --git a/lib/arel/nodes/case.rb b/lib/arel/nodes/case.rb
index 85f8851dbe..1edca40001 100644
--- a/lib/arel/nodes/case.rb
+++ b/lib/arel/nodes/case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Case < Arel::Nodes::Node
diff --git a/lib/arel/nodes/casted.rb b/lib/arel/nodes/casted.rb
index 6b15f9e4b3..290e4dd38c 100644
--- a/lib/arel/nodes/casted.rb
+++ b/lib/arel/nodes/casted.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Casted < Arel::Nodes::Node # :nodoc:
diff --git a/lib/arel/nodes/count.rb b/lib/arel/nodes/count.rb
index 5c8ade1cf9..a7c6236a22 100644
--- a/lib/arel/nodes/count.rb
+++ b/lib/arel/nodes/count.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Count < Arel::Nodes::Function
diff --git a/lib/arel/nodes/delete_statement.rb b/lib/arel/nodes/delete_statement.rb
index 8aaf8ca0b6..593ce9bddf 100644
--- a/lib/arel/nodes/delete_statement.rb
+++ b/lib/arel/nodes/delete_statement.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class DeleteStatement < Arel::Nodes::Binary
diff --git a/lib/arel/nodes/descending.rb b/lib/arel/nodes/descending.rb
index d886bdcb5f..d7261ab583 100644
--- a/lib/arel/nodes/descending.rb
+++ b/lib/arel/nodes/descending.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Descending < Ordering
diff --git a/lib/arel/nodes/equality.rb b/lib/arel/nodes/equality.rb
index f29344e580..ef44725e24 100644
--- a/lib/arel/nodes/equality.rb
+++ b/lib/arel/nodes/equality.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Equality < Arel::Nodes::Binary
diff --git a/lib/arel/nodes/extract.rb b/lib/arel/nodes/extract.rb
index 7ed678ca08..4e797b6770 100644
--- a/lib/arel/nodes/extract.rb
+++ b/lib/arel/nodes/extract.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Extract < Arel::Nodes::Unary
diff --git a/lib/arel/nodes/false.rb b/lib/arel/nodes/false.rb
index 6df70e43ce..26b4e5db97 100644
--- a/lib/arel/nodes/false.rb
+++ b/lib/arel/nodes/false.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class False < Arel::Nodes::Node
diff --git a/lib/arel/nodes/full_outer_join.rb b/lib/arel/nodes/full_outer_join.rb
index 708f161c9a..12a02d8cd9 100644
--- a/lib/arel/nodes/full_outer_join.rb
+++ b/lib/arel/nodes/full_outer_join.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class FullOuterJoin < Arel::Nodes::Join
diff --git a/lib/arel/nodes/function.rb b/lib/arel/nodes/function.rb
index 182dfa7329..28a394e9f3 100644
--- a/lib/arel/nodes/function.rb
+++ b/lib/arel/nodes/function.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Function < Arel::Nodes::Node
diff --git a/lib/arel/nodes/grouping.rb b/lib/arel/nodes/grouping.rb
index e7f4bd9cd5..16911eb3b6 100644
--- a/lib/arel/nodes/grouping.rb
+++ b/lib/arel/nodes/grouping.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Grouping < Unary
diff --git a/lib/arel/nodes/in.rb b/lib/arel/nodes/in.rb
index 6ccf37a053..30cd771c40 100644
--- a/lib/arel/nodes/in.rb
+++ b/lib/arel/nodes/in.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class In < Equality
diff --git a/lib/arel/nodes/infix_operation.rb b/lib/arel/nodes/infix_operation.rb
index 55ac715f73..4eb7c5356f 100644
--- a/lib/arel/nodes/infix_operation.rb
+++ b/lib/arel/nodes/infix_operation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
 
diff --git a/lib/arel/nodes/inner_join.rb b/lib/arel/nodes/inner_join.rb
index bf10eeac18..4e398267c3 100644
--- a/lib/arel/nodes/inner_join.rb
+++ b/lib/arel/nodes/inner_join.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class InnerJoin < Arel::Nodes::Join
diff --git a/lib/arel/nodes/insert_statement.rb b/lib/arel/nodes/insert_statement.rb
index ada4fcc562..72793bc1ad 100644
--- a/lib/arel/nodes/insert_statement.rb
+++ b/lib/arel/nodes/insert_statement.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class InsertStatement < Arel::Nodes::Node
diff --git a/lib/arel/nodes/join_source.rb b/lib/arel/nodes/join_source.rb
index da828cf9ee..428ce8183e 100644
--- a/lib/arel/nodes/join_source.rb
+++ b/lib/arel/nodes/join_source.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     ###
diff --git a/lib/arel/nodes/matches.rb b/lib/arel/nodes/matches.rb
index 0d9c1925dc..3ad3850a8e 100644
--- a/lib/arel/nodes/matches.rb
+++ b/lib/arel/nodes/matches.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Matches < Binary
diff --git a/lib/arel/nodes/named_function.rb b/lib/arel/nodes/named_function.rb
index c792f0af98..173838a7fd 100644
--- a/lib/arel/nodes/named_function.rb
+++ b/lib/arel/nodes/named_function.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class NamedFunction < Arel::Nodes::Function
diff --git a/lib/arel/nodes/node.rb b/lib/arel/nodes/node.rb
index 239c4fd766..34e71063af 100644
--- a/lib/arel/nodes/node.rb
+++ b/lib/arel/nodes/node.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'arel/collectors/sql_string'
 
 module Arel
diff --git a/lib/arel/nodes/outer_join.rb b/lib/arel/nodes/outer_join.rb
index bea5578b95..c568655fe6 100644
--- a/lib/arel/nodes/outer_join.rb
+++ b/lib/arel/nodes/outer_join.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class OuterJoin < Arel::Nodes::Join
diff --git a/lib/arel/nodes/over.rb b/lib/arel/nodes/over.rb
index 21d1b5029e..47a34e69ea 100644
--- a/lib/arel/nodes/over.rb
+++ b/lib/arel/nodes/over.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
 
diff --git a/lib/arel/nodes/regexp.rb b/lib/arel/nodes/regexp.rb
index 784368f5bf..8a76185ef0 100644
--- a/lib/arel/nodes/regexp.rb
+++ b/lib/arel/nodes/regexp.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Regexp < Binary
diff --git a/lib/arel/nodes/right_outer_join.rb b/lib/arel/nodes/right_outer_join.rb
index ea1ddb7d52..04ab31ebf0 100644
--- a/lib/arel/nodes/right_outer_join.rb
+++ b/lib/arel/nodes/right_outer_join.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class RightOuterJoin < Arel::Nodes::Join
diff --git a/lib/arel/nodes/select_core.rb b/lib/arel/nodes/select_core.rb
index 3696dd20af..264fa46591 100644
--- a/lib/arel/nodes/select_core.rb
+++ b/lib/arel/nodes/select_core.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class SelectCore < Arel::Nodes::Node
diff --git a/lib/arel/nodes/select_statement.rb b/lib/arel/nodes/select_statement.rb
index 830ac27046..641a08405d 100644
--- a/lib/arel/nodes/select_statement.rb
+++ b/lib/arel/nodes/select_statement.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class SelectStatement < Arel::Nodes::Node
diff --git a/lib/arel/nodes/sql_literal.rb b/lib/arel/nodes/sql_literal.rb
index 2c56644b99..73575a7d49 100644
--- a/lib/arel/nodes/sql_literal.rb
+++ b/lib/arel/nodes/sql_literal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class SqlLiteral < String
diff --git a/lib/arel/nodes/string_join.rb b/lib/arel/nodes/string_join.rb
index 7fb0033c0f..21d6845c45 100644
--- a/lib/arel/nodes/string_join.rb
+++ b/lib/arel/nodes/string_join.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class StringJoin < Arel::Nodes::Join
diff --git a/lib/arel/nodes/table_alias.rb b/lib/arel/nodes/table_alias.rb
index a5adc0766a..78deb175b6 100644
--- a/lib/arel/nodes/table_alias.rb
+++ b/lib/arel/nodes/table_alias.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class TableAlias < Arel::Nodes::Binary
diff --git a/lib/arel/nodes/terminal.rb b/lib/arel/nodes/terminal.rb
index f4cdfdfe17..6f60fe006f 100644
--- a/lib/arel/nodes/terminal.rb
+++ b/lib/arel/nodes/terminal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Distinct < Arel::Nodes::Node
diff --git a/lib/arel/nodes/true.rb b/lib/arel/nodes/true.rb
index 082963e5e6..796b5b9348 100644
--- a/lib/arel/nodes/true.rb
+++ b/lib/arel/nodes/true.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class True < Arel::Nodes::Node
diff --git a/lib/arel/nodes/unary.rb b/lib/arel/nodes/unary.rb
index 50946980b4..a42744b1d5 100644
--- a/lib/arel/nodes/unary.rb
+++ b/lib/arel/nodes/unary.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Unary < Arel::Nodes::Node
diff --git a/lib/arel/nodes/unary_operation.rb b/lib/arel/nodes/unary_operation.rb
index 1636c01279..3c56ef2026 100644
--- a/lib/arel/nodes/unary_operation.rb
+++ b/lib/arel/nodes/unary_operation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
 
diff --git a/lib/arel/nodes/unqualified_column.rb b/lib/arel/nodes/unqualified_column.rb
index 2820dba9d2..f9017238c8 100644
--- a/lib/arel/nodes/unqualified_column.rb
+++ b/lib/arel/nodes/unqualified_column.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class UnqualifiedColumn < Arel::Nodes::Unary
diff --git a/lib/arel/nodes/update_statement.rb b/lib/arel/nodes/update_statement.rb
index d6831dc242..286f0bd3ce 100644
--- a/lib/arel/nodes/update_statement.rb
+++ b/lib/arel/nodes/update_statement.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class UpdateStatement < Arel::Nodes::Node
diff --git a/lib/arel/nodes/values.rb b/lib/arel/nodes/values.rb
index 814e843dab..b32d5063a2 100644
--- a/lib/arel/nodes/values.rb
+++ b/lib/arel/nodes/values.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Values < Arel::Nodes::Binary
diff --git a/lib/arel/nodes/window.rb b/lib/arel/nodes/window.rb
index fee8eeff7a..535c0c6238 100644
--- a/lib/arel/nodes/window.rb
+++ b/lib/arel/nodes/window.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class Window < Arel::Nodes::Node
diff --git a/lib/arel/nodes/with.rb b/lib/arel/nodes/with.rb
index 7f08abe47d..def7840ea3 100644
--- a/lib/arel/nodes/with.rb
+++ b/lib/arel/nodes/with.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Nodes
     class With < Arel::Nodes::Unary
diff --git a/lib/arel/order_predications.rb b/lib/arel/order_predications.rb
index 153fcffb41..d84be82bb6 100644
--- a/lib/arel/order_predications.rb
+++ b/lib/arel/order_predications.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module OrderPredications
 
diff --git a/lib/arel/predications.rb b/lib/arel/predications.rb
index 81bf3b4d95..799c7c67b8 100644
--- a/lib/arel/predications.rb
+++ b/lib/arel/predications.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Predications
     def not_eq other
diff --git a/lib/arel/select_manager.rb b/lib/arel/select_manager.rb
index 6af9b6fbe6..0b35176842 100644
--- a/lib/arel/select_manager.rb
+++ b/lib/arel/select_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'arel/collectors/sql_string'
 
 module Arel
diff --git a/lib/arel/table.rb b/lib/arel/table.rb
index 130b7ea028..b3f2d79e5f 100644
--- a/lib/arel/table.rb
+++ b/lib/arel/table.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   class Table
     include Arel::Crud
diff --git a/lib/arel/tree_manager.rb b/lib/arel/tree_manager.rb
index 5278ab06a1..cc3f1eeee4 100644
--- a/lib/arel/tree_manager.rb
+++ b/lib/arel/tree_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'arel/collectors/sql_string'
 
 module Arel
diff --git a/lib/arel/update_manager.rb b/lib/arel/update_manager.rb
index 36fb74fe7c..eac414eafb 100644
--- a/lib/arel/update_manager.rb
+++ b/lib/arel/update_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   class UpdateManager < Arel::TreeManager
     def initialize
diff --git a/lib/arel/visitors.rb b/lib/arel/visitors.rb
index 9bf5170463..a3404cf992 100644
--- a/lib/arel/visitors.rb
+++ b/lib/arel/visitors.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'arel/visitors/visitor'
 require 'arel/visitors/depth_first'
 require 'arel/visitors/to_sql'
diff --git a/lib/arel/visitors/bind_substitute.rb b/lib/arel/visitors/bind_substitute.rb
index ce0fb5c924..52c96b0d72 100644
--- a/lib/arel/visitors/bind_substitute.rb
+++ b/lib/arel/visitors/bind_substitute.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Visitors
     class BindSubstitute
diff --git a/lib/arel/visitors/depth_first.rb b/lib/arel/visitors/depth_first.rb
index 69ed345aea..5416a285f5 100644
--- a/lib/arel/visitors/depth_first.rb
+++ b/lib/arel/visitors/depth_first.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Visitors
     class DepthFirst < Arel::Visitors::Visitor
diff --git a/lib/arel/visitors/reduce.rb b/lib/arel/visitors/reduce.rb
index 9670cad27c..7948758e2f 100644
--- a/lib/arel/visitors/reduce.rb
+++ b/lib/arel/visitors/reduce.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'arel/visitors/visitor'
 
 module Arel
diff --git a/lib/arel/visitors/visitor.rb b/lib/arel/visitors/visitor.rb
index bfe7342f04..b96b8238a7 100644
--- a/lib/arel/visitors/visitor.rb
+++ b/lib/arel/visitors/visitor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module Visitors
     class Visitor
diff --git a/lib/arel/window_predications.rb b/lib/arel/window_predications.rb
index 71844eab53..f93dede036 100644
--- a/lib/arel/window_predications.rb
+++ b/lib/arel/window_predications.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module Arel
   module WindowPredications
 
diff --git a/test/attributes/test_attribute.rb b/test/attributes/test_attribute.rb
index 928b23ed7b..2b971ce54a 100644
--- a/test/attributes/test_attribute.rb
+++ b/test/attributes/test_attribute.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 require 'ostruct'
 
diff --git a/test/collectors/test_bind_collector.rb b/test/collectors/test_bind_collector.rb
index fc7df2fc45..877aa20043 100644
--- a/test/collectors/test_bind_collector.rb
+++ b/test/collectors/test_bind_collector.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 require 'arel/collectors/bind'
 
diff --git a/test/collectors/test_sql_string.rb b/test/collectors/test_sql_string.rb
index 37a9e41f71..92f1bf0fba 100644
--- a/test/collectors/test_sql_string.rb
+++ b/test/collectors/test_sql_string.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 require 'arel/collectors/bind'
 
diff --git a/test/helper.rb b/test/helper.rb
index 6e8ac836fc..022ba1dae6 100644
--- a/test/helper.rb
+++ b/test/helper.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'rubygems'
 require 'minitest/autorun'
 require 'fileutils'
diff --git a/test/nodes/test_and.rb b/test/nodes/test_and.rb
index 88d6d61531..8d1980269c 100644
--- a/test/nodes/test_and.rb
+++ b/test/nodes/test_and.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_as.rb b/test/nodes/test_as.rb
index b1dcccf7c7..1240d2333f 100644
--- a/test/nodes/test_as.rb
+++ b/test/nodes/test_as.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_ascending.rb b/test/nodes/test_ascending.rb
index 2991d46583..9b0e5f0c18 100644
--- a/test/nodes/test_ascending.rb
+++ b/test/nodes/test_ascending.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_bin.rb b/test/nodes/test_bin.rb
index 0dcc5f7bb8..af27d827fd 100644
--- a/test/nodes/test_bin.rb
+++ b/test/nodes/test_bin.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_binary.rb b/test/nodes/test_binary.rb
index 7e25a21151..8e3025a440 100644
--- a/test/nodes/test_binary.rb
+++ b/test/nodes/test_binary.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 require 'set'
 
diff --git a/test/nodes/test_bind_param.rb b/test/nodes/test_bind_param.rb
index ea008f4c99..011de6410c 100644
--- a/test/nodes/test_bind_param.rb
+++ b/test/nodes/test_bind_param.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_case.rb b/test/nodes/test_case.rb
index a813ec7e69..21ff670e05 100644
--- a/test/nodes/test_case.rb
+++ b/test/nodes/test_case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_casted.rb b/test/nodes/test_casted.rb
index 6d775e17ec..748879a538 100644
--- a/test/nodes/test_casted.rb
+++ b/test/nodes/test_casted.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_count.rb b/test/nodes/test_count.rb
index a9a329420e..85e93b1927 100644
--- a/test/nodes/test_count.rb
+++ b/test/nodes/test_count.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 describe Arel::Nodes::Count do
diff --git a/test/nodes/test_delete_statement.rb b/test/nodes/test_delete_statement.rb
index 4bd5446ba2..5ce51a9ae8 100644
--- a/test/nodes/test_delete_statement.rb
+++ b/test/nodes/test_delete_statement.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 describe Arel::Nodes::DeleteStatement do
diff --git a/test/nodes/test_descending.rb b/test/nodes/test_descending.rb
index fce71d69e9..98de94910f 100644
--- a/test/nodes/test_descending.rb
+++ b/test/nodes/test_descending.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_distinct.rb b/test/nodes/test_distinct.rb
index ffa8a68e6c..6c51b99946 100644
--- a/test/nodes/test_distinct.rb
+++ b/test/nodes/test_distinct.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_equality.rb b/test/nodes/test_equality.rb
index 42a156b051..83f73f1789 100644
--- a/test/nodes/test_equality.rb
+++ b/test/nodes/test_equality.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_extract.rb b/test/nodes/test_extract.rb
index eb98553268..307ef2572c 100644
--- a/test/nodes/test_extract.rb
+++ b/test/nodes/test_extract.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 describe Arel::Nodes::Extract do
diff --git a/test/nodes/test_false.rb b/test/nodes/test_false.rb
index a2a8866680..da65e71547 100644
--- a/test/nodes/test_false.rb
+++ b/test/nodes/test_false.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_grouping.rb b/test/nodes/test_grouping.rb
index febf0bee40..8379336109 100644
--- a/test/nodes/test_grouping.rb
+++ b/test/nodes/test_grouping.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_infix_operation.rb b/test/nodes/test_infix_operation.rb
index 40616024e5..b6c891a5c0 100644
--- a/test/nodes/test_infix_operation.rb
+++ b/test/nodes/test_infix_operation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_insert_statement.rb b/test/nodes/test_insert_statement.rb
index e0a5696ea4..af2c9541cb 100644
--- a/test/nodes/test_insert_statement.rb
+++ b/test/nodes/test_insert_statement.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 describe Arel::Nodes::InsertStatement do
diff --git a/test/nodes/test_named_function.rb b/test/nodes/test_named_function.rb
index 33830d9d43..1f765e822d 100644
--- a/test/nodes/test_named_function.rb
+++ b/test/nodes/test_named_function.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_node.rb b/test/nodes/test_node.rb
index 056df7a584..2fd27600be 100644
--- a/test/nodes/test_node.rb
+++ b/test/nodes/test_node.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_not.rb b/test/nodes/test_not.rb
index a08d037445..cd027cec16 100644
--- a/test/nodes/test_not.rb
+++ b/test/nodes/test_not.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_or.rb b/test/nodes/test_or.rb
index 3e7bcc9379..6bc02c0ad3 100644
--- a/test/nodes/test_or.rb
+++ b/test/nodes/test_or.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_over.rb b/test/nodes/test_over.rb
index 0aac00b230..183c02fad3 100644
--- a/test/nodes/test_over.rb
+++ b/test/nodes/test_over.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 describe Arel::Nodes::Over do
diff --git a/test/nodes/test_select_core.rb b/test/nodes/test_select_core.rb
index 4114bcf4ff..f868a2f940 100644
--- a/test/nodes/test_select_core.rb
+++ b/test/nodes/test_select_core.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_select_statement.rb b/test/nodes/test_select_statement.rb
index 3e4fcc0c07..ae209b86fd 100644
--- a/test/nodes/test_select_statement.rb
+++ b/test/nodes/test_select_statement.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 describe Arel::Nodes::SelectStatement do
diff --git a/test/nodes/test_sql_literal.rb b/test/nodes/test_sql_literal.rb
index c09e5882d5..74e4f2cc90 100644
--- a/test/nodes/test_sql_literal.rb
+++ b/test/nodes/test_sql_literal.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 require 'yaml'
 
diff --git a/test/nodes/test_sum.rb b/test/nodes/test_sum.rb
index d387e7f9ef..e1b65abbef 100644
--- a/test/nodes/test_sum.rb
+++ b/test/nodes/test_sum.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 describe Arel::Nodes::Sum do
diff --git a/test/nodes/test_table_alias.rb b/test/nodes/test_table_alias.rb
index 57c9a42fc6..39040e6352 100644
--- a/test/nodes/test_table_alias.rb
+++ b/test/nodes/test_table_alias.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 require 'ostruct'
 
diff --git a/test/nodes/test_true.rb b/test/nodes/test_true.rb
index ed4743a63b..35b4d0a14d 100644
--- a/test/nodes/test_true.rb
+++ b/test/nodes/test_true.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_unary_operation.rb b/test/nodes/test_unary_operation.rb
index d89c10b431..bde9594a2c 100644
--- a/test/nodes/test_unary_operation.rb
+++ b/test/nodes/test_unary_operation.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/nodes/test_update_statement.rb b/test/nodes/test_update_statement.rb
index 920dc6e3ef..09a4a09074 100644
--- a/test/nodes/test_update_statement.rb
+++ b/test/nodes/test_update_statement.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 describe Arel::Nodes::UpdateStatement do
diff --git a/test/nodes/test_window.rb b/test/nodes/test_window.rb
index 9ec42be59f..b4ad22edb5 100644
--- a/test/nodes/test_window.rb
+++ b/test/nodes/test_window.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/support/fake_record.rb b/test/support/fake_record.rb
index 4867dad5dc..03116ff2ee 100644
--- a/test/support/fake_record.rb
+++ b/test/support/fake_record.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 module FakeRecord
   class Column < Struct.new(:name, :type)
   end
diff --git a/test/test_attributes.rb b/test/test_attributes.rb
index d0b00d4333..754fc0c134 100644
--- a/test/test_attributes.rb
+++ b/test/test_attributes.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/test_crud.rb b/test/test_crud.rb
index 5c470155ac..0832f82aee 100644
--- a/test/test_crud.rb
+++ b/test/test_crud.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/test_delete_manager.rb b/test/test_delete_manager.rb
index ece2389d88..2d068d3b8b 100644
--- a/test/test_delete_manager.rb
+++ b/test/test_delete_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/test_factory_methods.rb b/test/test_factory_methods.rb
index 3e23b090b4..3dbe2d615d 100644
--- a/test/test_factory_methods.rb
+++ b/test/test_factory_methods.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/test_insert_manager.rb b/test/test_insert_manager.rb
index 4289b0fa8c..f6a76fc20f 100644
--- a/test/test_insert_manager.rb
+++ b/test/test_insert_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/test_select_manager.rb b/test/test_select_manager.rb
index e88f0e8e11..076b732984 100644
--- a/test/test_select_manager.rb
+++ b/test/test_select_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/test_table.rb b/test/test_table.rb
index e36a6e3a41..9877d24541 100644
--- a/test/test_table.rb
+++ b/test/test_table.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/test_update_manager.rb b/test/test_update_manager.rb
index f41dc46e7d..85abbf3875 100644
--- a/test/test_update_manager.rb
+++ b/test/test_update_manager.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/visitors/test_bind_visitor.rb b/test/visitors/test_bind_visitor.rb
index f0007cabbf..3e0578a6a1 100644
--- a/test/visitors/test_bind_visitor.rb
+++ b/test/visitors/test_bind_visitor.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 require 'arel/visitors/bind_visitor'
 require 'support/fake_record'
diff --git a/test/visitors/test_depth_first.rb b/test/visitors/test_depth_first.rb
index 81220b63a4..0c7f7ccd34 100644
--- a/test/visitors/test_depth_first.rb
+++ b/test/visitors/test_depth_first.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 require 'set'
 
diff --git a/test/visitors/test_dispatch_contamination.rb b/test/visitors/test_dispatch_contamination.rb
index d3c9e8af2e..6422a6dff3 100644
--- a/test/visitors/test_dispatch_contamination.rb
+++ b/test/visitors/test_dispatch_contamination.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/visitors/test_dot.rb b/test/visitors/test_dot.rb
index 179a2c297c..1d27d1a5cb 100644
--- a/test/visitors/test_dot.rb
+++ b/test/visitors/test_dot.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/visitors/test_ibm_db.rb b/test/visitors/test_ibm_db.rb
index f1aa7612be..81a5713183 100644
--- a/test/visitors/test_ibm_db.rb
+++ b/test/visitors/test_ibm_db.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/visitors/test_informix.rb b/test/visitors/test_informix.rb
index 04c42f8f60..9d15979219 100644
--- a/test/visitors/test_informix.rb
+++ b/test/visitors/test_informix.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/visitors/test_mssql.rb b/test/visitors/test_mssql.rb
index fe228bce4b..0d0753b14b 100644
--- a/test/visitors/test_mssql.rb
+++ b/test/visitors/test_mssql.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/visitors/test_mysql.rb b/test/visitors/test_mysql.rb
index 30dcea3d36..9a205311d4 100644
--- a/test/visitors/test_mysql.rb
+++ b/test/visitors/test_mysql.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/visitors/test_oracle.rb b/test/visitors/test_oracle.rb
index 4c22be5cbb..b1921f0cbc 100644
--- a/test/visitors/test_oracle.rb
+++ b/test/visitors/test_oracle.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/visitors/test_oracle12.rb b/test/visitors/test_oracle12.rb
index 43235fd72c..c908a51d4f 100644
--- a/test/visitors/test_oracle12.rb
+++ b/test/visitors/test_oracle12.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/visitors/test_postgres.rb b/test/visitors/test_postgres.rb
index f97b734b7d..26cc721871 100644
--- a/test/visitors/test_postgres.rb
+++ b/test/visitors/test_postgres.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/visitors/test_sqlite.rb b/test/visitors/test_sqlite.rb
index a9f3501f20..2e145b3faa 100644
--- a/test/visitors/test_sqlite.rb
+++ b/test/visitors/test_sqlite.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 
 module Arel
diff --git a/test/visitors/test_to_sql.rb b/test/visitors/test_to_sql.rb
index e31d60366b..07458c1dc5 100644
--- a/test/visitors/test_to_sql.rb
+++ b/test/visitors/test_to_sql.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 require 'helper'
 require 'set'
 
-- 
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