Merge pull request #29506 from pat/frozen-string-literals

Make ActiveSupport frozen-string-literal friendly.

actionmailer/test/base_test.rb

@@ -120,7 +120,7 @@ class BaseTest < ActiveSupport::TestCase
     email = BaseMailer.attachment_with_hash
     assert_equal(1, email.attachments.length)
     assert_equal("invoice.jpg", email.attachments[0].filename)
-    expected = "\312\213\254\232)b"
+    expected = "\312\213\254\232)b".dup
     expected.force_encoding(Encoding::BINARY)
     assert_equal expected, email.attachments["invoice.jpg"].decoded
   end
@@ -129,7 +129,7 @@ class BaseTest < ActiveSupport::TestCase
     email = BaseMailer.attachment_with_hash_default_encoding
     assert_equal(1, email.attachments.length)
     assert_equal("invoice.jpg", email.attachments[0].filename)
-    expected = "\312\213\254\232)b"
+    expected = "\312\213\254\232)b".dup
     expected.force_encoding(Encoding::BINARY)
     assert_equal expected, email.attachments["invoice.jpg"].decoded
   end

actionpack/lib/action_controller/log_subscriber.rb

@@ -24,7 +24,7 @@ def process_action(event)
           exception_class_name = payload[:exception].first
           status = ActionDispatch::ExceptionWrapper.status_code_for_exception(exception_class_name)
         end
-        message = "Completed #{status} #{Rack::Utils::HTTP_STATUS_CODES[status]} in #{event.duration.round}ms"
+        message = "Completed #{status} #{Rack::Utils::HTTP_STATUS_CODES[status]} in #{event.duration.round}ms".dup
         message << " (#{additions.join(" | ".freeze)})" unless additions.empty?
         message << "\n\n" if defined?(Rails.env) && Rails.env.development?
 

actionpack/lib/action_dispatch/http/response.rb

@@ -103,7 +103,7 @@ def initialize(response, buf)
 
       def body
         @str_body ||= begin
-          buf = ""
+          buf = "".dup
           each { |chunk| buf << chunk }
           buf
         end

actionpack/lib/action_dispatch/journey/router/utils.rb

@@ -14,11 +14,11 @@ class Utils # :nodoc:
         #   normalize_path("/%ab")  # => "/%AB"
         def self.normalize_path(path)
           encoding = path.encoding
-          path = "/#{path}"
+          path = "/#{path}".dup
           path.squeeze!("/".freeze)
           path.sub!(%r{/+\Z}, "".freeze)
           path.gsub!(/(%[a-f0-9]{2})/) { $1.upcase }
-          path = "/" if path == "".freeze
+          path = "/".dup if path == "".freeze
           path.force_encoding(encoding)
           path
         end
@@ -29,7 +29,7 @@ class UriEncoder # :nodoc:
           ENCODE   = "%%%02X".freeze
           US_ASCII = Encoding::US_ASCII
           UTF_8    = Encoding::UTF_8
-          EMPTY    = "".force_encoding(US_ASCII).freeze
+          EMPTY    = "".dup.force_encoding(US_ASCII).freeze
           DEC2HEX  = (0..255).to_a.map { |i| ENCODE % i }.map { |s| s.force_encoding(US_ASCII) }
 
           ALPHA = "a-zA-Z".freeze

actionpack/lib/action_dispatch/testing/assertions/response.rb

@@ -79,7 +79,7 @@ def normalize_argument_to_redirection(fragment)
         def generate_response_message(expected, actual = @response.response_code)
           "Expected response to be a <#{code_with_name(expected)}>,"\
           " but was a <#{code_with_name(actual)}>"
-            .concat(location_if_redirected).concat(response_body_if_short)
+            .dup.concat(location_if_redirected).concat(response_body_if_short)
         end
 
         def response_body_if_short

actionview/lib/action_view/helpers/date_helper.rb

@@ -1007,7 +1007,7 @@ def build_select(type, select_options_as_html)
           select_options[:disabled] = "disabled" if @options[:disabled]
           select_options[:class] = css_class_attribute(type, select_options[:class], @options[:with_css_classes]) if @options[:with_css_classes]
 
-          select_html = "\n"
+          select_html = "\n".dup
           select_html << content_tag("option".freeze, "", value: "") + "\n" if @options[:include_blank]
           select_html << prompt_option_tag(type, @options[:prompt]) + "\n" if @options[:prompt]
           select_html << select_options_as_html
@@ -1089,7 +1089,7 @@ def input_id_from_type(type)
         # Given an ordering of datetime components, create the selection HTML
         # and join them with their appropriate separators.
         def build_selects_from_types(order)
-          select = ""
+          select = "".dup
           first_visible = order.find { |type| !@options[:"discard_#{type}"] }
           order.reverse_each do |type|
             separator = separator(type) unless type == first_visible # don't add before first visible field

actionview/lib/action_view/helpers/javascript_helper.rb

@@ -13,8 +13,8 @@ module JavaScriptHelper
         "'"     => "\\'"
       }
 
-      JS_ESCAPE_MAP["\342\200\250".force_encoding(Encoding::UTF_8).encode!] = "
"
-      JS_ESCAPE_MAP["\342\200\251".force_encoding(Encoding::UTF_8).encode!] = "
"
+      JS_ESCAPE_MAP["\342\200\250".dup.force_encoding(Encoding::UTF_8).encode!] = "
"
+      JS_ESCAPE_MAP["\342\200\251".dup.force_encoding(Encoding::UTF_8).encode!] = "
"
 
       # Escapes carriage returns and single and double quotes for JavaScript segments.
       #

actionview/lib/action_view/helpers/translation_helper.rb

@@ -95,7 +95,7 @@ def translate(key, options = {})
           raise e if raise_error
 
           keys = I18n.normalize_keys(e.locale, e.key, e.options[:scope])
-          title = "translation missing: #{keys.join('.')}"
+          title = "translation missing: #{keys.join('.')}".dup
 
           interpolations = options.except(:default, :scope)
           if interpolations.any?

actionview/lib/action_view/log_subscriber.rb

@@ -14,7 +14,7 @@ def initialize
 
     def render_template(event)
       info do
-        message = "  Rendered #{from_rails_root(event.payload[:identifier])}"
+        message = "  Rendered #{from_rails_root(event.payload[:identifier])}".dup
         message << " within #{from_rails_root(event.payload[:layout])}" if event.payload[:layout]
         message << " (#{event.duration.round(1)}ms)"
       end
@@ -22,7 +22,7 @@ def render_template(event)
 
     def render_partial(event)
       info do
-        message = "  Rendered #{from_rails_root(event.payload[:identifier])}"
+        message = "  Rendered #{from_rails_root(event.payload[:identifier])}".dup
         message << " within #{from_rails_root(event.payload[:layout])}" if event.payload[:layout]
         message << " (#{event.duration.round(1)}ms)"
         message << " #{cache_message(event.payload)}" unless event.payload[:cache_hit].nil?

actionview/lib/action_view/template.rb

@@ -282,7 +282,7 @@ def compile(mod)
 
         # Make sure that the resulting String to be eval'd is in the
         # encoding of the code
-        source = <<-end_src
+        source = <<-end_src.dup
           def #{method_name}(local_assigns, output_buffer)
             _old_virtual_path, @virtual_path = @virtual_path, #{@virtual_path.inspect};_old_output_buffer = @output_buffer;#{locals_code};#{code}
           ensure
@@ -329,12 +329,12 @@ def locals_code
         locals = locals.grep(/\A@?(?![A-Z0-9])(?:[[:alnum:]_]|[^\0-\177])+\z/)
 
         # Double assign to suppress the dreaded 'assigned but unused variable' warning
-        locals.each_with_object("") { |key, code| code << "#{key} = #{key} = local_assigns[:#{key}];" }
+        locals.each_with_object("".dup) { |key, code| code << "#{key} = #{key} = local_assigns[:#{key}];" }
       end
 
       def method_name
         @method_name ||= begin
-          m = "_#{identifier_method_name}__#{@identifier.hash}_#{__id__}"
+          m = "_#{identifier_method_name}__#{@identifier.hash}_#{__id__}".dup
           m.tr!("-".freeze, "_".freeze)
           m
         end

actionview/lib/action_view/template/resolver.rb

@@ -14,7 +14,7 @@ class Path
       alias_method :partial?, :partial
 
       def self.build(name, prefix, partial)
-        virtual = ""
+        virtual = "".dup
         virtual << "#{prefix}/" unless prefix.empty?
         virtual << (partial ? "_#{name}" : name)
         new name, prefix, partial, virtual

actionview/lib/action_view/test_case.rb

@@ -104,7 +104,7 @@ def setup_with_controller
         # empty string ensures buffer has UTF-8 encoding as
         # new without arguments returns ASCII-8BIT encoded buffer like String#new
         @output_buffer = ActiveSupport::SafeBuffer.new ""
-        @rendered = ""
+        @rendered = "".dup
 
         make_test_case_available_to_view!
         say_no_to_protect_against_forgery!

actionview/lib/action_view/testing/resolvers.rb

@@ -20,7 +20,7 @@ def to_s
     private
 
       def query(path, exts, _, _)
-        query = ""
+        query = "".dup
         EXTENSIONS.each_key do |ext|
           query << "(" << exts[ext].map { |e| e && Regexp.escape(".#{e}") }.join("|") << "|)"
         end

actionview/test/activerecord/form_helper_activerecord_test.rb

@@ -55,7 +55,7 @@ def test_nested_fields_for_with_child_index_option_override_on_a_nested_attribut
   private
 
     def hidden_fields(method = nil)
-      txt = %{<input name="utf8" type="hidden" value="&#x2713;" />}
+      txt = %{<input name="utf8" type="hidden" value="&#x2713;" />}.dup
 
       if method && !%w(get post).include?(method.to_s)
         txt << %{<input name="_method" type="hidden" value="#{method}" />}
@@ -65,7 +65,7 @@ def hidden_fields(method = nil)
     end
 
     def form_text(action = "/", id = nil, html_class = nil, remote = nil, multipart = nil, method = nil)
-      txt =  %{<form accept-charset="UTF-8" action="#{action}"}
+      txt =  %{<form accept-charset="UTF-8" action="#{action}"}.dup
       txt << %{ enctype="multipart/form-data"} if multipart
       txt << %{ data-remote="true"} if remote
       txt << %{ class="#{html_class}"} if html_class

actionview/test/fixtures/ruby_template.ruby

-body = ""
+body = "".dup
 body << ["Hello", "from", "Ruby", "code"].join(" ")

actionview/test/template/atom_feed_helper_test.rb

@@ -194,7 +194,7 @@ class ScrollsController < ActionController::Base
   FEEDS["provide_builder"] = <<-'EOT'
           # we pass in the new_xml to the helper so it doesn't
           # call anything on the original builder
-          new_xml = Builder::XmlMarkup.new(:target=>'')
+          new_xml = Builder::XmlMarkup.new(:target=>''.dup)
           atom_feed(:xml => new_xml) do |feed|
             feed.title("My great blog!")
             feed.updated(@scrolls.first.created_at)

actionview/test/template/form_helper/form_with_test.rb

@@ -16,7 +16,7 @@ def hidden_fields(options = {})
     method = options[:method]
     skip_enforcing_utf8 = options.fetch(:skip_enforcing_utf8, false)
 
-    "".tap do |txt|
+    "".dup.tap do |txt|
       unless skip_enforcing_utf8
         txt << %{<input name="utf8" type="hidden" value="&#x2713;" />}
       end
@@ -32,7 +32,7 @@ def form_text(action = "http://www.example.com", local: false, **options)
 
     method = method.to_s == "get" ? "get" : "post"
 
-    txt =  %{<form accept-charset="UTF-8" action="#{action}"}
+    txt =  %{<form accept-charset="UTF-8" action="#{action}"}.dup
     txt << %{ enctype="multipart/form-data"} if enctype
     txt << %{ data-remote="true"} unless local
     txt << %{ class="#{html_class}"} if html_class
@@ -2194,9 +2194,9 @@ def hidden_fields(options = {})
       method = options[:method]
 
       if options.fetch(:skip_enforcing_utf8, false)
-        txt = ""
+        txt = "".dup
       else
-        txt = %{<input name="utf8" type="hidden" value="&#x2713;" />}
+        txt = %{<input name="utf8" type="hidden" value="&#x2713;" />}.dup
       end
 
       if method && !%w(get post).include?(method.to_s)
@@ -2207,7 +2207,7 @@ def hidden_fields(options = {})
     end
 
     def form_text(action = "/", id = nil, html_class = nil, local = nil, multipart = nil, method = nil)
-      txt =  %{<form accept-charset="UTF-8" action="#{action}"}
+      txt =  %{<form accept-charset="UTF-8" action="#{action}"}.dup
       txt << %{ enctype="multipart/form-data"} if multipart
       txt << %{ data-remote="true"} unless local
       txt << %{ class="#{html_class}"} if html_class

actionview/test/template/form_helper_test.rb

@@ -3446,9 +3446,9 @@ def hidden_fields(options = {})
       method = options[:method]
 
       if options.fetch(:enforce_utf8, true)
-        txt = %{<input name="utf8" type="hidden" value="&#x2713;" />}
+        txt = %{<input name="utf8" type="hidden" value="&#x2713;" />}.dup
       else
-        txt = ""
+        txt = "".dup
       end
 
       if method && !%w(get post).include?(method.to_s)
@@ -3459,7 +3459,7 @@ def hidden_fields(options = {})
     end
 
     def form_text(action = "/", id = nil, html_class = nil, remote = nil, multipart = nil, method = nil)
-      txt =  %{<form accept-charset="UTF-8" action="#{action}"}
+      txt =  %{<form accept-charset="UTF-8" action="#{action}"}.dup
       txt << %{ enctype="multipart/form-data"} if multipart
       txt << %{ data-remote="true"} if remote
       txt << %{ class="#{html_class}"} if html_class

actionview/test/template/form_tag_helper_test.rb

@@ -14,7 +14,7 @@ def hidden_fields(options = {})
     method = options[:method]
     enforce_utf8 = options.fetch(:enforce_utf8, true)
 
-    "".tap do |txt|
+    "".dup.tap do |txt|
       if enforce_utf8
         txt << %{<input name="utf8" type="hidden" value="&#x2713;" />}
       end
@@ -30,7 +30,7 @@ def form_text(action = "http://www.example.com", options = {})
 
     method = method.to_s == "get" ? "get" : "post"
 
-    txt =  %{<form accept-charset="UTF-8" action="#{action}"}
+    txt =  %{<form accept-charset="UTF-8" action="#{action}"}.dup
     txt << %{ enctype="multipart/form-data"} if enctype
     txt << %{ data-remote="true"} if remote
     txt << %{ class="#{html_class}"} if html_class

actionview/test/template/javascript_helper_test.rb

@@ -20,8 +20,8 @@ def test_escape_javascript
     assert_equal %(This \\"thing\\" is really\\n netos\\'), escape_javascript(%(This "thing" is really\n netos'))
     assert_equal %(backslash\\\\test), escape_javascript(%(backslash\\test))
     assert_equal %(dont <\\/close> tags), escape_javascript(%(dont </close> tags))
-    assert_equal %(unicode &#x2028; newline), escape_javascript(%(unicode \342\200\250 newline).force_encoding(Encoding::UTF_8).encode!)
-    assert_equal %(unicode &#x2029; newline), escape_javascript(%(unicode \342\200\251 newline).force_encoding(Encoding::UTF_8).encode!)
+    assert_equal %(unicode &#x2028; newline), escape_javascript(%(unicode \342\200\250 newline).dup.force_encoding(Encoding::UTF_8).encode!)
+    assert_equal %(unicode &#x2029; newline), escape_javascript(%(unicode \342\200\251 newline).dup.force_encoding(Encoding::UTF_8).encode!)
 
     assert_equal %(dont <\\/close> tags), j(%(dont </close> tags))
   end

actionview/test/template/render_test.rb

@@ -439,7 +439,7 @@ def test_render_fallbacks_to_erb_for_unknown_types
   end
 
   CustomHandler = lambda do |template|
-    "@output_buffer = ''\n" \
+    "@output_buffer = ''.dup\n" \
       "@output_buffer << 'source: #{template.source.inspect}'\n"
   end
 
@@ -583,7 +583,7 @@ def test_render_layout_with_object
 
   def test_render_with_passing_couple_extensions_to_one_register_template_handler_function_call
     ActionView::Template.register_template_handler :foo1, :foo2, CustomHandler
-    assert_equal @view.render(inline: "Hello, World!", type: :foo1), @view.render(inline: "Hello, World!", type: :foo2)
+    assert_equal @view.render(inline: "Hello, World!".dup, type: :foo1), @view.render(inline: "Hello, World!".dup, type: :foo2)
   ensure
     ActionView::Template.unregister_template_handler :foo1, :foo2
   end

actionview/test/template/streaming_render_test.rb

@@ -17,7 +17,7 @@ def render_body(options)
 
   def buffered_render(options)
     body = render_body(options)
-    string = ""
+    string = "".dup
     body.each do |piece|
       string << piece
     end

actionview/test/template/template_test.rb

@@ -53,7 +53,7 @@ def my_buffer
   end
 
   def new_template(body = "<%= hello %>", details = { format: :html })
-    ActionView::Template.new(body, "hello template", details.fetch(:handler) { ERBHandler }, { virtual_path: "hello" }.merge!(details))
+    ActionView::Template.new(body.dup, "hello template", details.fetch(:handler) { ERBHandler }, { virtual_path: "hello" }.merge!(details))
   end
 
   def render(locals = {})

actionview/test/template/text_helper_test.rb

@@ -11,7 +11,7 @@ def setup
   end
 
   def test_concat
-    self.output_buffer = "foo"
+    self.output_buffer = "foo".dup
     assert_equal "foobar", concat("bar")
     assert_equal "foobar", output_buffer
   end
@@ -104,8 +104,8 @@ def test_truncate_with_options_hash
   end
 
   def test_truncate_multibyte
-    assert_equal "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 ...".force_encoding(Encoding::UTF_8),
-      truncate("\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 \354\225\204\353\235\274\353\246\254\354\230\244".force_encoding(Encoding::UTF_8), length: 10)
+    assert_equal "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 ...".dup.force_encoding(Encoding::UTF_8),
+      truncate("\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 \354\225\204\353\235\274\353\246\254\354\230\244".dup.force_encoding(Encoding::UTF_8), length: 10)
   end
 
   def test_truncate_does_not_modify_the_options_hash
@@ -325,7 +325,7 @@ def test_excerpt_with_omission
   end
 
   def test_excerpt_with_utf8
-    assert_equal("...\357\254\203ciency could not be...".force_encoding(Encoding::UTF_8), excerpt("That's why e\357\254\203ciency could not be helped".force_encoding(Encoding::UTF_8), "could", radius: 8))
+    assert_equal("...\357\254\203ciency could not be...".dup.force_encoding(Encoding::UTF_8), excerpt("That's why e\357\254\203ciency could not be helped".dup.force_encoding(Encoding::UTF_8), "could", radius: 8))
   end
 
   def test_excerpt_does_not_modify_the_options_hash

actionview/test/template/url_helper_test.rb

@@ -539,7 +539,7 @@ def test_current_page_with_escaped_params
 
   def test_current_page_with_escaped_params_with_different_encoding
     @request = request_for_url("/")
-    @request.stub(:path, "/category/administra%c3%a7%c3%a3o".force_encoding(Encoding::ASCII_8BIT)) do
+    @request.stub(:path, "/category/administra%c3%a7%c3%a3o".dup.force_encoding(Encoding::ASCII_8BIT)) do
       assert current_page?(controller: "foo", action: "category", category: "administração")
       assert current_page?("http://www.example.com/category/administra%c3%a7%c3%a3o")
     end

activemodel/test/cases/dirty_test.rb

@@ -96,7 +96,7 @@ def reload
   end
 
   test "attribute mutation" do
-    @model.instance_variable_set("@name", "Yam")
+    @model.instance_variable_set("@name", "Yam".dup)
     assert !@model.name_changed?
     @model.name.replace("Hadad")
     assert !@model.name_changed?

activemodel/test/cases/type/string_test.rb

@@ -14,7 +14,7 @@ class StringTest < ActiveModel::TestCase
       test "cast strings are mutable" do
         type = Type::String.new
 
-        s = "foo"
+        s = "foo".dup
         assert_equal false, type.cast(s).frozen?
         assert_equal false, s.frozen?
 

activerecord/lib/active_record/associations/join_dependency.rb

@@ -198,8 +198,7 @@ def construct_tables!(parent, node)
 
         def table_alias_for(reflection, parent, join)
           name = "#{reflection.plural_name}_#{parent.table_name}"
-          name << "_join" if join
-          name
+          join ? "#{name}_join" : name
         end
 
         def walk(left, right)

activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

@@ -679,7 +679,7 @@ def checkout_for_exclusive_access(checkout_timeout)
           # this block can't be easily moved into attempt_to_checkout_all_existing_connections's
           # rescue block, because doing so would put it outside of synchronize section, without
           # being in a critical section thread_report might become inaccurate
-          msg = "could not obtain ownership of all database connections in #{checkout_timeout} seconds"
+          msg = "could not obtain ownership of all database connections in #{checkout_timeout} seconds".dup
 
           thread_report = []
           @connections.each do |conn|

activerecord/lib/active_record/connection_adapters/abstract/schema_creation.rb

@@ -22,7 +22,7 @@ def accept(o)
         private
 
           def visit_AlterTable(o)
-            sql = "ALTER TABLE #{quote_table_name(o.name)} "
+            sql = "ALTER TABLE #{quote_table_name(o.name)} ".dup
             sql << o.adds.map { |col| accept col }.join(" ")
             sql << o.foreign_key_adds.map { |fk| visit_AddForeignKey fk }.join(" ")
             sql << o.foreign_key_drops.map { |fk| visit_DropForeignKey fk }.join(" ")
@@ -30,17 +30,17 @@ def visit_AlterTable(o)
 
           def visit_ColumnDefinition(o)
             o.sql_type = type_to_sql(o.type, o.options)
-            column_sql = "#{quote_column_name(o.name)} #{o.sql_type}"
+            column_sql = "#{quote_column_name(o.name)} #{o.sql_type}".dup
             add_column_options!(column_sql, column_options(o)) unless o.type == :primary_key
             column_sql
           end
 
           def visit_AddColumnDefinition(o)
-            "ADD #{accept(o.column)}"
+            "ADD #{accept(o.column)}".dup
           end
 
           def visit_TableDefinition(o)
-            create_sql = "CREATE#{' TEMPORARY' if o.temporary} TABLE #{quote_table_name(o.name)} "
+            create_sql = "CREATE#{' TEMPORARY' if o.temporary} TABLE #{quote_table_name(o.name)} ".dup
 
             statements = o.columns.map { |c| accept c }
             statements << accept(o.primary_keys) if o.primary_keys

activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb

@@ -1348,7 +1348,7 @@ def insert_versions_sql(versions)
           sm_table = quote_table_name(ActiveRecord::SchemaMigration.table_name)
 
           if versions.is_a?(Array)
-            sql = "INSERT INTO #{sm_table} (version) VALUES\n"
+            sql = "INSERT INTO #{sm_table} (version) VALUES\n".dup
             sql << versions.map { |v| "(#{quote(v)})" }.join(",\n")
             sql << ";\n\n"
             sql

activerecord/lib/active_record/connection_adapters/abstract_adapter.rb

@@ -147,7 +147,7 @@ def valid_type?(type) # :nodoc:
       # this method must only be called while holding connection pool's mutex
       def lease
         if in_use?
-          msg = "Cannot lease connection, "
+          msg = "Cannot lease connection, ".dup
           if @owner == Thread.current
             msg << "it is already leased by the current thread."
           else

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -132,7 +132,7 @@ def native_database_types
       end
 
       def index_algorithms
-        { default: "ALGORITHM = DEFAULT", copy: "ALGORITHM = COPY", inplace: "ALGORITHM = INPLACE" }
+        { default: "ALGORITHM = DEFAULT".dup, copy: "ALGORITHM = COPY".dup, inplace: "ALGORITHM = INPLACE".dup }
       end
 
       # HELPER METHODS ===========================================
@@ -379,7 +379,7 @@ def rename_column(table_name, column_name, new_column_name) #:nodoc:
 
       def add_index(table_name, column_name, options = {}) #:nodoc:
         index_name, index_type, index_columns, _, index_algorithm, index_using, comment = add_index_options(table_name, column_name, options)
-        sql = "CREATE #{index_type} INDEX #{quote_column_name(index_name)} #{index_using} ON #{quote_table_name(table_name)} (#{index_columns}) #{index_algorithm}"
+        sql = "CREATE #{index_type} INDEX #{quote_column_name(index_name)} #{index_using} ON #{quote_table_name(table_name)} (#{index_columns}) #{index_algorithm}".dup
         execute add_sql_comment!(sql, comment)
       end
 
@@ -464,7 +464,7 @@ def type_to_sql(type, limit: nil, precision: nil, scale: nil, unsigned: nil, **)
             super
           end
 
-        sql << " unsigned" if unsigned && type != :primary_key
+        sql = "#{sql} unsigned" if unsigned && type != :primary_key
         sql
       end
 
@@ -778,7 +778,7 @@ def configure_connection
           # http://dev.mysql.com/doc/refman/5.7/en/set-statement.html#id944430
           # (trailing comma because variable_assignments will always have content)
           if @config[:encoding]
-            encoding = "NAMES #{@config[:encoding]}"
+            encoding = "NAMES #{@config[:encoding]}".dup
             encoding << " COLLATE #{@config[:collation]}" if @config[:collation]
             encoding << ", "
           end

activerecord/lib/active_record/connection_adapters/mysql/schema_creation.rb

@@ -16,7 +16,7 @@ def visit_AddColumnDefinition(o)
           end
 
           def visit_ChangeColumnDefinition(o)
-            change_column_sql = "CHANGE #{quote_column_name(o.name)} #{accept(o.column)}"
+            change_column_sql = "CHANGE #{quote_column_name(o.name)} #{accept(o.column)}".dup
             add_column_position!(change_column_sql, column_options(o.column))
           end
 
@@ -63,7 +63,7 @@ def add_column_position!(sql, options)
 
           def index_in_create(table_name, column_name, options)
             index_name, index_type, index_columns, _, _, index_using, comment = @conn.add_index_options(table_name, column_name, options)
-            add_sql_comment!("#{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns})", comment)
+            add_sql_comment!("#{index_type} INDEX #{quote_column_name(index_name)} #{index_using} (#{index_columns})".dup, comment)
           end
       end
     end

activerecord/lib/active_record/connection_adapters/mysql/schema_statements.rb

@@ -102,7 +102,7 @@ def extract_foreign_key_action(specifier)
           def data_source_sql(name = nil, type: nil)
             scope = quoted_scope(name, type: type)
 
-            sql = "SELECT table_name FROM information_schema.tables"
+            sql = "SELECT table_name FROM information_schema.tables".dup
             sql << " WHERE table_schema = #{scope[:schema]}"
             sql << " AND table_name = #{scope[:name]}" if scope[:name]
             sql << " AND table_type = #{scope[:type]}" if scope[:type]

activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb

@@ -406,7 +406,7 @@ def change_column(table_name, column_name, type, options = {}) #:nodoc:
           quoted_table_name = quote_table_name(table_name)
           quoted_column_name = quote_column_name(column_name)
           sql_type = type_to_sql(type, options)
-          sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quoted_column_name} TYPE #{sql_type}"
+          sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quoted_column_name} TYPE #{sql_type}".dup
           if options[:collation]
             sql << " COLLATE \"#{options[:collation]}\""
           end
@@ -566,7 +566,7 @@ def type_to_sql(type, limit: nil, precision: nil, scale: nil, array: nil, **) #
               super
             end
 
-          sql << "[]" if array && type != :primary_key
+          sql = "#{sql}[]" if array && type != :primary_key
           sql
         end
 
@@ -635,7 +635,7 @@ def data_source_sql(name = nil, type: nil)
             scope = quoted_scope(name, type: type)
             scope[:type] ||= "'r','v','m'" # (r)elation/table, (v)iew, (m)aterialized view
 
-            sql = "SELECT c.relname FROM pg_class c LEFT JOIN pg_namespace n ON n.oid = c.relnamespace"
+            sql = "SELECT c.relname FROM pg_class c LEFT JOIN pg_namespace n ON n.oid = c.relnamespace".dup
             sql << " WHERE n.nspname = #{scope[:schema]}"
             sql << " AND c.relname = #{scope[:name]}" if scope[:name]
             sql << " AND c.relkind IN (#{scope[:type]})"

activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb

@@ -67,7 +67,7 @@ def data_source_sql(name = nil, type: nil)
             scope = quoted_scope(name, type: type)
             scope[:type] ||= "'table','view'"
 
-            sql = "SELECT name FROM sqlite_master WHERE name <> 'sqlite_sequence'"
+            sql = "SELECT name FROM sqlite_master WHERE name <> 'sqlite_sequence'".dup
             sql << " AND name = #{scope[:name]}" if scope[:name]
             sql << " AND type IN (#{scope[:type]})"
             sql

activerecord/lib/active_record/explain.rb

@@ -16,7 +16,7 @@ def collecting_queries_for_explain # :nodoc:
     # Returns a formatted string ready to be logged.
     def exec_explain(queries) # :nodoc:
       str = queries.map do |sql, binds|
-        msg = "EXPLAIN for: #{sql}"
+        msg = "EXPLAIN for: #{sql}".dup
         unless binds.empty?
           msg << " "
           msg << binds.map { |attr| render_bind(attr) }.inspect

activerecord/lib/active_record/migration.rb

@@ -157,7 +157,7 @@ def initialize
 
   class ProtectedEnvironmentError < ActiveRecordError #:nodoc:
     def initialize(env = "production")
-      msg = "You are attempting to run a destructive action against your '#{env}' database.\n"
+      msg = "You are attempting to run a destructive action against your '#{env}' database.\n".dup
       msg << "If you are sure you want to continue, run the same command with the environment variable:\n"
       msg << "DISABLE_DATABASE_ENVIRONMENT_CHECK=1"
       super(msg)
@@ -166,7 +166,7 @@ def initialize(env = "production")
 
   class EnvironmentMismatchError < ActiveRecordError
     def initialize(current: nil, stored: nil)
-      msg =  "You are attempting to modify a database that was last run in `#{ stored }` environment.\n"
+      msg =  "You are attempting to modify a database that was last run in `#{ stored }` environment.\n".dup
       msg << "You are running in `#{ current }` environment. "
       msg << "If you are sure you want to continue, first set the environment using:\n\n"
       msg << "        bin/rails db:environment:set"
@@ -1239,7 +1239,7 @@ def execute_migration_in_transaction(migration, direction)
           record_version_state_after_migrating(migration.version)
         end
       rescue => e
-        msg = "An error has occurred, "
+        msg = "An error has occurred, ".dup
         msg << "this and " if use_transaction?(migration)
         msg << "all later migrations canceled:\n\n#{e}"
         raise StandardError, msg, e.backtrace

activerecord/lib/active_record/relation/finder_methods.rb

@@ -334,14 +334,14 @@ def raise_record_not_found_exception!(ids = nil, result_size = nil, expected_siz
       name = @klass.name
 
       if ids.nil?
-        error = "Couldn't find #{name}"
+        error = "Couldn't find #{name}".dup
         error << " with#{conditions}" if conditions
         raise RecordNotFound.new(error, name)
       elsif Array(ids).size == 1
         error = "Couldn't find #{name} with '#{key}'=#{ids}#{conditions}"
         raise RecordNotFound.new(error, name, key, ids)
       else
-        error = "Couldn't find all #{name.pluralize} with '#{key}': "
+        error = "Couldn't find all #{name.pluralize} with '#{key}': ".dup
         error << "(#{ids.join(", ")})#{conditions} (found #{result_size} results, but was looking for #{expected_size})"
 
         raise RecordNotFound.new(error, name, primary_key, ids)

activerecord/lib/active_record/tasks/mysql_database_tasks.rb

@@ -151,7 +151,7 @@ def run_cmd(cmd, args, action)
         end
 
         def run_cmd_error(cmd, args, action)
-          msg = "failed to execute: `#{cmd}`\n"
+          msg = "failed to execute: `#{cmd}`\n".dup
           msg << "Please check the output above for any errors and make sure that `#{cmd}` is installed in your PATH and has proper permissions.\n\n"
           msg
         end

activerecord/test/cases/adapters/postgresql/bytea_test.rb

@@ -47,7 +47,7 @@ def test_type_cast_binary_converts_the_encoding
   end
 
   def test_type_cast_binary_value
-    data = "\u001F\x8B".force_encoding("BINARY")
+    data = "\u001F\x8B".dup.force_encoding("BINARY")
     assert_equal(data, @type.deserialize(data))
   end
 

activerecord/test/cases/adapters/postgresql/money_test.rb

@@ -47,10 +47,10 @@ def test_money_values
 
   def test_money_type_cast
     type = PostgresqlMoney.type_for_attribute("wealth")
-    assert_equal(12345678.12, type.cast("$12,345,678.12"))
-    assert_equal(12345678.12, type.cast("$12.345.678,12"))
-    assert_equal(-1.15, type.cast("-$1.15"))
-    assert_equal(-2.25, type.cast("($2.25)"))
+    assert_equal(12345678.12, type.cast("$12,345,678.12".dup))
+    assert_equal(12345678.12, type.cast("$12.345.678,12".dup))
+    assert_equal(-1.15, type.cast("-$1.15".dup))
+    assert_equal(-2.25, type.cast("($2.25)".dup))
   end
 
   def test_schema_dumping
@@ -60,7 +60,7 @@ def test_schema_dumping
   end
 
   def test_create_and_update_money
-    money = PostgresqlMoney.create(wealth: "987.65")
+    money = PostgresqlMoney.create(wealth: "987.65".dup)
     assert_equal 987.65, money.wealth
 
     new_value = BigDecimal.new("123.45")

activerecord/test/cases/adapters/sqlite3/sqlite3_adapter_test.rb

@@ -165,7 +165,7 @@ def test_quote_binary_column_escapes_it
             data binary
           )
         eosql
-        str = "\x80".force_encoding("ASCII-8BIT")
+        str = "\x80".dup.force_encoding("ASCII-8BIT")
         binary = DualEncoding.new name: "いただきます！", data: str
         binary.save!
         assert_equal str, binary.data
@@ -174,7 +174,7 @@ def test_quote_binary_column_escapes_it
       end
 
       def test_type_cast_should_not_mutate_encoding
-        name = "hello".force_encoding(Encoding::ASCII_8BIT)
+        name = "hello".dup.force_encoding(Encoding::ASCII_8BIT)
         Owner.create(name: name)
         assert_equal Encoding::ASCII_8BIT, name.encoding
       ensure

activerecord/test/cases/attribute_test.rb

@@ -76,7 +76,7 @@ class AttributeTest < ActiveRecord::TestCase
     end
 
     test "duping dups the value" do
-      @type.expect(:deserialize, "type cast", ["a value"])
+      @type.expect(:deserialize, "type cast".dup, ["a value"])
       attribute = Attribute.from_database(nil, "a value", @type)
 
       value_from_orig = attribute.value
@@ -244,7 +244,7 @@ def assert_valid_value(*)
     end
 
     test "with_type preserves mutations" do
-      attribute = Attribute.from_database(:foo, "", Type::Value.new)
+      attribute = Attribute.from_database(:foo, "".dup, Type::Value.new)
       attribute.value << "1"
 
       assert_equal 1, attribute.with_type(Type::Integer.new).value

activerecord/test/cases/batches_test.rb

@@ -152,7 +152,7 @@ def test_find_in_batches_should_quote_batch_order
   end
 
   def test_find_in_batches_should_not_use_records_after_yielding_them_in_case_original_array_is_modified
-    not_a_post = "not a post"
+    not_a_post = "not a post".dup
     def not_a_post.id; end
     not_a_post.stub(:id, -> { raise StandardError.new("not_a_post had #id called on it") }) do
       assert_nothing_raised do
@@ -417,7 +417,7 @@ def test_in_batches_should_quote_batch_order
   end
 
   def test_in_batches_should_not_use_records_after_yielding_them_in_case_original_array_is_modified
-    not_a_post = "not a post"
+    not_a_post = "not a post".dup
     def not_a_post.id
       raise StandardError.new("not_a_post had #id called on it")
     end

activerecord/test/cases/binary_test.rb

@@ -10,7 +10,7 @@ class BinaryTest < ActiveRecord::TestCase
     FIXTURES = %w(flowers.jpg example.log test.txt)
 
     def test_mixed_encoding
-      str = "\x80"
+      str = "\x80".dup
       str.force_encoding("ASCII-8BIT")
 
       binary = Binary.new name: "いただきます！", data: str

activerecord/test/cases/core_test.rb

@@ -35,7 +35,7 @@ def test_inspect_class_without_table
 
   def test_pretty_print_new
     topic = Topic.new
-    actual = ""
+    actual = "".dup
     PP.pp(topic, StringIO.new(actual))
     expected = <<-PRETTY.strip_heredoc
     #<Topic:0xXXXXXX
@@ -64,7 +64,7 @@ def test_pretty_print_new
 
   def test_pretty_print_persisted
     topic = topics(:first)
-    actual = ""
+    actual = "".dup
     PP.pp(topic, StringIO.new(actual))
     expected = <<-PRETTY.strip_heredoc
     #<Topic:0x\\w+
@@ -92,7 +92,7 @@ def test_pretty_print_persisted
 
   def test_pretty_print_uninitialized
     topic = Topic.allocate
-    actual = ""
+    actual = "".dup
     PP.pp(topic, StringIO.new(actual))
     expected = "#<Topic:XXXXXX not initialized>\n"
     assert actual.start_with?(expected.split("XXXXXX").first)
@@ -105,7 +105,7 @@ def inspect
         "inspecting topic"
       end
     end
-    actual = ""
+    actual = "".dup
     PP.pp(subtopic.new, StringIO.new(actual))
     assert_equal "inspecting topic\n", actual
   end

activesupport/lib/active_support/cache.rb

@@ -75,7 +75,7 @@ def lookup_store(*store_option)
       #
       # The +key+ argument can also respond to +cache_key+ or +to_param+.
       def expand_cache_key(key, namespace = nil)
-        expanded_cache_key = namespace ? "#{namespace}/" : ""
+        expanded_cache_key = (namespace ? "#{namespace}/" : "").dup
 
         if prefix = ENV["RAILS_CACHE_ID"] || ENV["RAILS_APP_VERSION"]
           expanded_cache_key << "#{prefix}/"

activesupport/lib/active_support/duration/iso8601_serializer.rb

@@ -15,12 +15,12 @@ def serialize
         parts, sign = normalize
         return "PT0S".freeze if parts.empty?
 
-        output = "P"
+        output = "P".dup
         output << "#{parts[:years]}Y"   if parts.key?(:years)
         output << "#{parts[:months]}M"  if parts.key?(:months)
         output << "#{parts[:weeks]}W"   if parts.key?(:weeks)
         output << "#{parts[:days]}D"    if parts.key?(:days)
-        time = ""
+        time = "".dup
         time << "#{parts[:hours]}H"     if parts.key?(:hours)
         time << "#{parts[:minutes]}M"   if parts.key?(:minutes)
         if parts.key?(:seconds)

activesupport/lib/active_support/message_encryptor.rb

@@ -114,7 +114,7 @@ def _encrypt(value)
         encrypted_data << cipher.final
 
         blob = "#{::Base64.strict_encode64 encrypted_data}--#{::Base64.strict_encode64 iv}"
-        blob << "--#{::Base64.strict_encode64 cipher.auth_tag}" if aead_mode?
+        blob = "#{blob}--#{::Base64.strict_encode64 cipher.auth_tag}" if aead_mode?
         blob
       end
 

activesupport/lib/active_support/number_helper/number_to_phone_converter.rb

@@ -2,7 +2,7 @@ module ActiveSupport
   module NumberHelper
     class NumberToPhoneConverter < NumberConverter #:nodoc:
       def convert
-        str = country_code(opts[:country_code])
+        str = country_code(opts[:country_code]).dup
         str << convert_to_phone_number(number.to_s.strip)
         str << phone_ext(opts[:extension])
       end

activesupport/lib/active_support/xml_mini/libxml.rb

@@ -53,7 +53,7 @@ def to_hash(hash = {})
           if c.element?
             c.to_hash(node_hash)
           elsif c.text? || c.cdata?
-            node_hash[CONTENT_ROOT] ||= ""
+            node_hash[CONTENT_ROOT] ||= "".dup
             node_hash[CONTENT_ROOT] << c.content
           end
         end

activesupport/lib/active_support/xml_mini/libxmlsax.rb

@@ -21,7 +21,7 @@ def current_hash
       end
 
       def on_start_document
-        @hash = { CONTENT_KEY => "" }
+        @hash = { CONTENT_KEY => "".dup }
         @hash_stack = [@hash]
       end
 
@@ -31,7 +31,7 @@ def on_end_document
       end
 
       def on_start_element(name, attrs = {})
-        new_hash = { CONTENT_KEY => "" }.merge!(attrs)
+        new_hash = { CONTENT_KEY => "".dup }.merge!(attrs)
         new_hash[HASH_SIZE_KEY] = new_hash.size + 1
 
         case current_hash[name]

activesupport/lib/active_support/xml_mini/nokogiri.rb

@@ -57,7 +57,7 @@ def to_hash(hash = {})
             if c.element?
               c.to_hash(node_hash)
             elsif c.text? || c.cdata?
-              node_hash[CONTENT_ROOT] ||= ""
+              node_hash[CONTENT_ROOT] ||= "".dup
               node_hash[CONTENT_ROOT] << c.content
             end
           end

activesupport/lib/active_support/xml_mini/nokogirisax.rb

@@ -37,7 +37,7 @@ def error(error_message)
       end
 
       def start_element(name, attrs = [])
-        new_hash = { CONTENT_KEY => "" }.merge!(Hash[attrs])
+        new_hash = { CONTENT_KEY => "".dup }.merge!(Hash[attrs])
         new_hash[HASH_SIZE_KEY] = new_hash.size + 1
 
         case current_hash[name]

activesupport/lib/active_support/xml_mini/rexml.rb

@@ -74,7 +74,7 @@ def merge_texts!(hash, element)
           hash
         else
           # must use value to prevent double-escaping
-          texts = ""
+          texts = "".dup
           element.texts.each { |t| texts << t.value }
           merge!(hash, CONTENT_KEY, texts)
         end

activesupport/test/cache/behaviors/cache_store_behavior.rb

@@ -196,7 +196,7 @@ def test_delete
   end
 
   def test_original_store_objects_should_not_be_immutable
-    bar = "bar"
+    bar = "bar".dup
     @cache.write("foo", bar)
     assert_nothing_raised { bar.gsub!(/.*/, "baz") }
   end
@@ -285,7 +285,7 @@ def test_crazy_key_characters
   end
 
   def test_really_long_keys
-    key = ""
+    key = "".dup
     900.times { key << "x" }
     assert @cache.write(key, "bar")
     assert_equal "bar", @cache.read(key)

activesupport/test/cache/behaviors/encoded_key_cache_behavior.rb

@@ -4,7 +4,7 @@
 module EncodedKeyCacheBehavior
   Encoding.list.each do |encoding|
     define_method "test_#{encoding.name.underscore}_encoded_values" do
-      key = "foo".force_encoding(encoding)
+      key = "foo".dup.force_encoding(encoding)
       assert @cache.write(key, "1", raw: true)
       assert_equal "1", @cache.read(key)
       assert_equal "1", @cache.fetch(key)
@@ -16,7 +16,7 @@ module EncodedKeyCacheBehavior
   end
 
   def test_common_utf8_values
-    key = "\xC3\xBCmlaut".force_encoding(Encoding::UTF_8)
+    key = "\xC3\xBCmlaut".dup.force_encoding(Encoding::UTF_8)
     assert @cache.write(key, "1", raw: true)
     assert_equal "1", @cache.read(key)
     assert_equal "1", @cache.fetch(key)
@@ -27,7 +27,7 @@ def test_common_utf8_values
   end
 
   def test_retains_encoding
-    key = "\xC3\xBCmlaut".force_encoding(Encoding::UTF_8)
+    key = "\xC3\xBCmlaut".dup.force_encoding(Encoding::UTF_8)
     assert @cache.write(key, "1", raw: true)
     assert_equal Encoding::UTF_8, key.encoding
   end

activesupport/test/cache/cache_key_test.rb

@@ -45,7 +45,7 @@ def test_expand_cache_key_rails_cache_id_should_win_over_rails_app_version
   end
 
   def test_expand_cache_key_respond_to_cache_key
-    key = "foo"
+    key = "foo".dup
     def key.cache_key
       :foo_key
     end
@@ -53,7 +53,7 @@ def key.cache_key
   end
 
   def test_expand_cache_key_array_with_something_that_responds_to_cache_key
-    key = "foo"
+    key = "foo".dup
     def key.cache_key
       :foo_key
     end

activesupport/test/core_ext/string_ext_test.rb

@@ -233,7 +233,7 @@ def test_starts_ends_with_alias
 
   def test_string_squish
     original = %{\u205f\u3000 A string surrounded by various unicode spaces,
-      with tabs(\t\t), newlines(\n\n), unicode nextlines(\u0085\u0085) and many spaces(  ). \u00a0\u2007}
+      with tabs(\t\t), newlines(\n\n), unicode nextlines(\u0085\u0085) and many spaces(  ). \u00a0\u2007}.dup
 
     expected = "A string surrounded by various unicode spaces, " \
       "with tabs( ), newlines( ), unicode nextlines( ) and many spaces( )."
@@ -303,8 +303,8 @@ def test_truncate_words_with_complex_string
   end
 
   def test_truncate_multibyte
-    assert_equal "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 ...".force_encoding(Encoding::UTF_8),
-      "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 \354\225\204\353\235\274\353\246\254\354\230\244".force_encoding(Encoding::UTF_8).truncate(10)
+    assert_equal "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 ...".dup.force_encoding(Encoding::UTF_8),
+      "\354\225\204\353\246\254\353\236\221 \354\225\204\353\246\254 \354\225\204\353\235\274\353\246\254\354\230\244".dup.force_encoding(Encoding::UTF_8).truncate(10)
   end
 
   def test_truncate_should_not_be_html_safe
@@ -325,7 +325,7 @@ def test_remove_for_multiple_occurrences
   end
 
   def test_remove!
-    original = "This is a very good day to die"
+    original = "This is a very good day to die".dup
     assert_equal "This is a good day to die", original.remove!(" very")
     assert_equal "This is a good day to die", original
     assert_equal "This is a good day", original.remove!(" to ", /die/)
@@ -658,7 +658,7 @@ def test_mb_chars_returns_instance_of_proxy_class
 
 class OutputSafetyTest < ActiveSupport::TestCase
   def setup
-    @string = "hello"
+    @string = "hello".dup
     @object = Class.new(Object) do
       def to_s
         "other"
@@ -734,7 +734,7 @@ def to_s
   end
 
   test "Concatting safe onto unsafe yields unsafe" do
-    @other_string = "other"
+    @other_string = "other".dup
 
     string = @string.html_safe
     @other_string.concat(string)
@@ -757,7 +757,7 @@ def to_s
   end
 
   test "Concatting safe onto unsafe with << yields unsafe" do
-    @other_string = "other"
+    @other_string = "other".dup
     string = @string.html_safe
 
     @other_string << string
@@ -813,7 +813,7 @@ def to_s
   test "Concatting an integer to safe always yields safe" do
     string = @string.html_safe
     string = string.concat(13)
-    assert_equal "hello".concat(13), string
+    assert_equal "hello".dup.concat(13), string
     assert string.html_safe?
   end
 
@@ -868,7 +868,8 @@ class StringExcludeTest < ActiveSupport::TestCase
 
 class StringIndentTest < ActiveSupport::TestCase
   test "does not indent strings that only contain newlines (edge cases)" do
-    ["", "\n", "\n" * 7].each do |str|
+    ["", "\n", "\n" * 7].each do |string|
+      str = string.dup
       assert_nil str.indent!(8)
       assert_equal str, str.indent(8)
       assert_equal str, str.indent(1, "\t")

activesupport/test/logger_test.rb

@@ -37,7 +37,7 @@ def test_write_binary_data_to_existing_file
     logger = Logger.new f
     logger.level = Logger::DEBUG
 
-    str = "\x80"
+    str = "\x80".dup
     str.force_encoding("ASCII-8BIT")
 
     logger.add Logger::DEBUG, str
@@ -55,7 +55,7 @@ def test_write_binary_data_create_file
     logger = Logger.new f
     logger.level = Logger::DEBUG
 
-    str = "\x80"
+    str = "\x80".dup
     str.force_encoding("ASCII-8BIT")
 
     logger.add Logger::DEBUG, str

activesupport/test/multibyte_chars_test.rb

@@ -51,7 +51,7 @@ def test_methods_are_forwarded_to_wrapped_string_for_byte_strings
   end
 
   def test_forwarded_method_with_non_string_result_should_be_returned_verbatim
-    str = ""
+    str = "".dup
     str.singleton_class.class_eval { def __method_for_multibyte_testing_with_integer_result; 1; end }
     @chars.wrapped_string.singleton_class.class_eval { def __method_for_multibyte_testing_with_integer_result; 1; end }
 
@@ -59,14 +59,14 @@ def test_forwarded_method_with_non_string_result_should_be_returned_verbatim
   end
 
   def test_should_concatenate
-    mb_a = "a".mb_chars
-    mb_b = "b".mb_chars
+    mb_a = "a".dup.mb_chars
+    mb_b = "b".dup.mb_chars
     assert_equal "ab", mb_a + "b"
     assert_equal "ab", "a" + mb_b
     assert_equal "ab", mb_a + mb_b
 
     assert_equal "ab", mb_a << "b"
-    assert_equal "ab", "a" << mb_b
+    assert_equal "ab", "a".dup << mb_b
     assert_equal "abb", mb_a << mb_b
   end
 
@@ -78,7 +78,7 @@ def test_consumes_utf8_strings
 
   def test_concatenation_should_return_a_proxy_class_instance
     assert_equal ActiveSupport::Multibyte.proxy_class, ("a".mb_chars + "b").class
-    assert_equal ActiveSupport::Multibyte.proxy_class, ("a".mb_chars << "b").class
+    assert_equal ActiveSupport::Multibyte.proxy_class, ("a".dup.mb_chars << "b").class
   end
 
   def test_ascii_strings_are_treated_at_utf8_strings
@@ -88,8 +88,8 @@ def test_ascii_strings_are_treated_at_utf8_strings
   def test_concatenate_should_return_proxy_instance
     assert(("a".mb_chars + "b").kind_of?(@proxy_class))
     assert(("a".mb_chars + "b".mb_chars).kind_of?(@proxy_class))
-    assert(("a".mb_chars << "b").kind_of?(@proxy_class))
-    assert(("a".mb_chars << "b".mb_chars).kind_of?(@proxy_class))
+    assert(("a".dup.mb_chars << "b").kind_of?(@proxy_class))
+    assert(("a".dup.mb_chars << "b".mb_chars).kind_of?(@proxy_class))
   end
 
   def test_should_return_string_as_json
@@ -115,12 +115,12 @@ def test_split_should_return_an_array_of_chars_instances
   %w{capitalize downcase lstrip reverse rstrip swapcase upcase}.each do |method|
     class_eval(<<-EOTESTS, __FILE__, __LINE__ + 1)
       def test_#{method}_bang_should_return_self_when_modifying_wrapped_string
-        chars = ' él piDió Un bUen café '
+        chars = ' él piDió Un bUen café '.dup
         assert_equal chars.object_id, chars.send("#{method}!").object_id
       end
 
       def test_#{method}_bang_should_change_wrapped_string
-        original = ' él piDió Un bUen café '
+        original = ' él piDió Un bUen café '.dup
         proxy = chars(original.dup)
         proxy.send("#{method}!")
         assert_not_equal original, proxy.to_s
@@ -133,7 +133,7 @@ def test_tidy_bytes_bang_should_return_self
   end
 
   def test_tidy_bytes_bang_should_change_wrapped_string
-    original = " Un bUen café \x92"
+    original = " Un bUen café \x92".dup
     proxy = chars(original.dup)
     proxy.tidy_bytes!
     assert_not_equal original, proxy.to_s
@@ -150,7 +150,7 @@ def test_identity
   end
 
   def test_string_methods_are_chainable
-    assert chars("").insert(0, "").kind_of?(ActiveSupport::Multibyte.proxy_class)
+    assert chars("".dup).insert(0, "").kind_of?(ActiveSupport::Multibyte.proxy_class)
     assert chars("").rjust(1).kind_of?(ActiveSupport::Multibyte.proxy_class)
     assert chars("").ljust(1).kind_of?(ActiveSupport::Multibyte.proxy_class)
     assert chars("").center(1).kind_of?(ActiveSupport::Multibyte.proxy_class)
@@ -195,7 +195,7 @@ def test_should_return_character_offset_for_regexp_matches
   end
 
   def test_should_use_character_offsets_for_insert_offsets
-    assert_equal "", "".mb_chars.insert(0, "")
+    assert_equal "", "".dup.mb_chars.insert(0, "")
     assert_equal "こわにちわ", @chars.insert(1, "わ")
     assert_equal "こわわわにちわ", @chars.insert(2, "わわ")
     assert_equal "わこわわわにちわ", @chars.insert(0, "わ")
@@ -418,13 +418,13 @@ def test_slice_bang_returns_nil_on_out_of_bound_arguments
   end
 
   def test_slice_bang_removes_the_slice_from_the_receiver
-    chars = "úüù".mb_chars
+    chars = "úüù".dup.mb_chars
     chars.slice!(0, 2)
     assert_equal "ù", chars
   end
 
   def test_slice_bang_returns_nil_and_does_not_modify_receiver_if_out_of_bounds
-    string = "úüù"
+    string = "úüù".dup
     chars = string.mb_chars
     assert_nil chars.slice!(4, 5)
     assert_equal "úüù", chars

activesupport/test/multibyte_test_helpers.rb

@@ -23,7 +23,7 @@ def self.download(from, to)
 
   UNICODE_STRING = "こにちわ".freeze
   ASCII_STRING = "ohayo".freeze
-  BYTE_STRING = "\270\236\010\210\245".force_encoding("ASCII-8BIT").freeze
+  BYTE_STRING = "\270\236\010\210\245".dup.force_encoding("ASCII-8BIT").freeze
 
   def chars(str)
     ActiveSupport::Multibyte::Chars.new(str)