Tightening the condition for including ActiveSupport::Testing::SetupA…

…ndTeardown::ForMiniTest.

[#1871 state:committed]

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

activesupport/lib/active_support/testing/setup_and_teardown.rb

@@ -8,7 +8,7 @@ def self.included(base)
           include ActiveSupport::Callbacks
           define_callbacks :setup, :teardown
 
-          if defined? MiniTest
+          if defined?(MiniTest::Assertions) && TestCase < MiniTest::Assertions
             include ForMiniTest
           else
             include ForClassicTestUnit