diff --git a/actionpack/lib/action_dispatch/testing/performance_test.rb b/actionpack/lib/action_dispatch/testing/performance_test.rb
index 33a5c68b9d..d6c98b4db7 100644
--- a/actionpack/lib/action_dispatch/testing/performance_test.rb
+++ b/actionpack/lib/action_dispatch/testing/performance_test.rb
@@ -11,9 +11,8 @@ module ActionDispatch
     # formats are written, so you'll have two output files per test method.
     class PerformanceTest < ActionDispatch::IntegrationTest
       include ActiveSupport::Testing::Performance
-      include ActiveSupport::Testing::Default
     end
   end
 rescue NameError
   $stderr.puts "Specify ruby-prof as application's dependency in Gemfile to run benchmarks."
-end
\ No newline at end of file
+end
diff --git a/activesupport/lib/active_support/test_case.rb b/activesupport/lib/active_support/test_case.rb
index ed8c02ba3e..fb52fc7083 100644
--- a/activesupport/lib/active_support/test_case.rb
+++ b/activesupport/lib/active_support/test_case.rb
@@ -24,8 +24,7 @@ class TestCase < ::Test::Unit::TestCase
     else
       Assertion = Test::Unit::AssertionFailedError
 
-      require 'active_support/testing/default'
-      include ActiveSupport::Testing::Default
+      undef :default_test
     end
 
     $tags = {}
diff --git a/activesupport/lib/active_support/testing/default.rb b/activesupport/lib/active_support/testing/default.rb
deleted file mode 100644
index a0bd6303c7..0000000000
--- a/activesupport/lib/active_support/testing/default.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-module ActiveSupport
-  module Testing
-    module Default #:nodoc:
-      # Placeholder so test/unit ignores test cases without any tests.
-      def default_test
-      end
-    end
-  end
-end
diff --git a/activesupport/test/test_test.rb b/activesupport/test/test_test.rb
index cdaf63961a..ee5a20c789 100644
--- a/activesupport/test/test_test.rb
+++ b/activesupport/test/test_test.rb
@@ -126,13 +126,6 @@ def test_assert_blank_false
   end
 end
 
-# These should always pass
-if ActiveSupport::Testing.const_defined?(:Default)
-  class NotTestingThingsTest < Test::Unit::TestCase
-    include ActiveSupport::Testing::Default
-  end
-end
-
 class AlsoDoingNothingTest < ActiveSupport::TestCase
 end