1 files changed, 12 insertions, 3 deletions
diff --git a/activesupport/lib/active_support/inflector/inflections.rb b/activesupport/lib/active_support/inflector/inflections.rb
index 90bb62f57b..13b23d627a 100644
--- a/activesupport/lib/active_support/inflector/inflections.rb
+++ b/activesupport/lib/active_support/inflector/inflections.rb
@@ -1,3 +1,5 @@
+require 'active_support/core_ext/array/prepend_and_append'
+
 module ActiveSupport
   module Inflector
     # A singleton instance of this class is yielded by Inflector.inflections, which can then be used to specify additional
@@ -26,6 +28,13 @@ module ActiveSupport
         @plurals, @singulars, @uncountables, @humans, @acronyms, @acronym_regex = [], [], [], [], {}, /(?=a)b/
       end
 
+      # Private, for the test suite.
+      def initialize_dup(orig)
+        %w(plurals singulars uncountables humans acronyms acronym_regex).each do |scope|
+          instance_variable_set("@#{scope}", orig.send(scope).dup)
+        end
+      end
+
       # Specifies a new acronym. An acronym must be specified as it will appear in a camelized string.  An underscore
       # string that contains the acronym will retain the acronym when passed to `camelize`, `humanize`, or `titleize`.
       # A camelized string that contains the acronym will maintain the acronym when titleized or humanized, and will
@@ -82,7 +91,7 @@ module ActiveSupport
       def plural(rule, replacement)
         @uncountables.delete(rule) if rule.is_a?(String)
         @uncountables.delete(replacement)
-        @plurals.insert(0, [rule, replacement])
+        @plurals.prepend([rule, replacement])
       end
 
       # Specifies a new singularization rule and its replacement. The rule can either be a string or a regular expression.
@@ -90,7 +99,7 @@ module ActiveSupport
       def singular(rule, replacement)
         @uncountables.delete(rule) if rule.is_a?(String)
         @uncountables.delete(replacement)
-        @singulars.insert(0, [rule, replacement])
+        @singulars.prepend([rule, replacement])
       end
 
       # Specifies a new irregular that applies to both pluralization and singularization at the same time. This can only be used
@@ -134,7 +143,7 @@ module ActiveSupport
       #   human /_cnt$/i, '\1_count'
       #   human "legacy_col_person_name", "Name"
       def human(rule, replacement)
-        @humans.insert(0, [rule, replacement])
+        @humans.prepend([rule, replacement])
       end
 
       # Clears the loaded inflections within a given scope (default is <tt>:all</tt>).