clean up test by using unregister method

actionpack/test/controller/mime_responds_test.rb

@@ -201,10 +201,8 @@ def setup
 
   def teardown
     super
-    Mime.module_eval { remove_const :IPHONE if const_defined?(:IPHONE) }
-    Mime.module_eval { remove_const :MOBILE if const_defined?(:MOBILE) }
-    Mime::LOOKUP.reject!{|key,_| key == 'text/x-mobile'}
-    Mime::LOOKUP.reject!{|key,_| key == 'text/iphone'}
+    Mime::Type.unregister('text/x-mobile', :iphone)
+    Mime::Type.unregister('text/iphone', :mobile)
   end
 
   def test_html
@@ -617,10 +615,8 @@ def setup
 
   def teardown
     super
-    Mime.module_eval { remove_const :IPHONE if const_defined?(:IPHONE) }
-    Mime.module_eval { remove_const :MOBILE if const_defined?(:MOBILE) }
-    Mime::LOOKUP.reject!{|key,_| key == 'text/x-mobile'}
-    Mime::LOOKUP.reject!{|key,_| key == 'text/iphone'}
+    Mime::Type.unregister('text/x-mobile', :iphone)
+    Mime::Type.unregister('text/iphone', :mobile)
   end
 
   def test_using_resource
@@ -1006,10 +1002,8 @@ def setup
 
   def teardown
     super
-    Mime.module_eval { remove_const :IPHONE if const_defined?(:IPHONE) }
-    Mime.module_eval { remove_const :MOBILE if const_defined?(:MOBILE) }
-    Mime::LOOKUP.reject!{|key,_| key == 'text/x-mobile'}
-    Mime::LOOKUP.reject!{|key,_| key == 'text/iphone'}
+    Mime::Type.unregister('text/x-mobile', :iphone)
+    Mime::Type.unregister('text/iphone', :mobile)
   end
 
   def test_missing_layout_renders_properly

actionpack/test/dispatch/mime_type_test.rb

@@ -85,8 +85,7 @@ class MimeTypeTest < ActiveSupport::TestCase
         assert_equal Mime::GIF, Mime::SET.last
       end
     ensure
-      Mime.module_eval { remove_const :GIF if const_defined?(:GIF) }
-      Mime::LOOKUP.reject!{|key,_| key == 'image/gif'}
+      Mime::Type.unregister('image/gif', :gif)
     end
   end