diff --git a/test/ruby/test_class.rb b/test/ruby/test_class.rb
index bc0f79a681..8d618822a5 100644
--- a/test/ruby/test_class.rb
+++ b/test/ruby/test_class.rb
@@ -98,11 +98,38 @@ class TestClass < Test::Unit::TestCase
     assert_equal(nil, BasicObject.superclass)
   end
 
+  def verbose_warning
+    class << (stderr = "")
+      alias write <<
+    end
+    stderr, $stderr, verbose, $VERBOSE = $stderr, stderr, $VERBOSE, true
+    yield
+  ensure
+    stderr, $stderr, $VERBOSE = $stderr, stderr, verbose
+    return stderr
+  end
+
   def test_module_function
     c = Class.new
     assert_raise(TypeError) do
       Module.instance_method(:module_function).bind(c).call(:foo)
     end
+
+    stderr = verbose_warning do
+      Module.new do
+        def foo; end
+        def foo; end
+      end
+    end
+    assert_match(/method redefined; discarding old foo/, stderr)
+    stderr = verbose_warning do
+      Module.new do
+        def foo; end
+        alias bar foo
+        alias bar foo
+      end
+    end
+    assert_equal("", stderr)
   end
 
   def test_check_inheritable