1 files changed, 20 insertions, 0 deletions
diff --git a/test/ruby/test_module.rb b/test/ruby/test_module.rb
index 6bbe168348..c7245ab2db 100644
--- a/test/ruby/test_module.rb
+++ b/test/ruby/test_module.rb
@@ -572,6 +572,26 @@ class TestModule < Test::Unit::TestCase
     assert_equal(2, a2.b)
   end
 
+  def test_ancestry_of_duped_classes
+    m = Module.new
+    sc = Class.new
+    a = Class.new(sc) do
+      def b; 2 end
+      prepend m
+    end
+
+    a2 = a.dup.new
+
+    assert_kind_of Object, a2
+    assert_kind_of sc, a2
+    refute_kind_of a, a2
+    assert_kind_of m, a2
+
+    assert_kind_of Class, a2.class
+    assert_kind_of sc.singleton_class, a2.class
+    assert_same sc, a2.class.superclass
+  end
+
   def test_gc_prepend_chain
     assert_separately([], <<-EOS)
       10000.times { |i|