1 files changed, 7 insertions, 0 deletions
diff --git a/actionpack/test/controller/middleware_stack_test.rb b/actionpack/test/controller/middleware_stack_test.rb
index 2a141697da..612a710fa7 100644
--- a/actionpack/test/controller/middleware_stack_test.rb
+++ b/actionpack/test/controller/middleware_stack_test.rb
@@ -73,4 +73,11 @@ class MiddlewareStackTest < ActiveSupport::TestCase
       end
     end
   end
+
+  test "lazy evaluates middleware class" do
+    assert_difference "@stack.size" do
+      @stack.use lambda { BazMiddleware }
+    end
+    assert_equal BazMiddleware, @stack.last.klass
+  end
 end