wrap test that changes inflections in with_dup

activesupport/test/inflector_test.rb

@@ -70,10 +70,11 @@ def test_uncountable_word_is_not_greedy
 
 
   def test_overwrite_previous_inflectors
-    assert_equal("series", ActiveSupport::Inflector.singularize("series"))
-    ActiveSupport::Inflector.inflections.singular "series", "serie"
-    assert_equal("serie", ActiveSupport::Inflector.singularize("series"))
-    ActiveSupport::Inflector.inflections.uncountable "series" # Return to normal
+    with_dup do
+      assert_equal("series", ActiveSupport::Inflector.singularize("series"))
+      ActiveSupport::Inflector.inflections.singular "series", "serie"
+      assert_equal("serie", ActiveSupport::Inflector.singularize("series"))
+    end
   end
 
   MixtureToTitleCase.each_with_index do |(before, titleized), index|

activesupport/test/inflector_test_cases.rb

@@ -63,6 +63,7 @@ module InflectorTestCases
     "news"        => "news",
 
     "series"      => "series",
+    "miniseries"  => "miniseries",
     "species"     => "species",
 
     "quiz"        => "quizzes",