Make add_metaclass copy __qualname__ from the original class. (#260)

Fixes #259.

2 files changed, 22 insertions, 0 deletions

diff --git a/six.py b/six.py
index 8d9ac41..901ec39 100644
--- a/six.py
+++ b/six.py
@@ -844,6 +844,8 @@ def add_metaclass(metaclass):
                 orig_vars.pop(slots_var)
         orig_vars.pop('__dict__', None)
         orig_vars.pop('__weakref__', None)
+        if hasattr(cls, '__qualname__'):
+            orig_vars['__qualname__'] = cls.__qualname__
         return metaclass(cls.__name__, cls.__bases__, orig_vars)
     return wrapper
 
diff --git a/test_six.py b/test_six.py
index 980cdf3..897e232 100644
--- a/test_six.py
+++ b/test_six.py
@@ -875,6 +875,26 @@ def test_add_metaclass():
     assert type(MySlotsWeakref) is Meta
 
 
+@py.test.mark.skipif("sys.version_info[:2] < (3, 3)")
+def test_add_metaclass_nested():
+    # Regression test for https://github.com/benjaminp/six/issues/259
+    class Meta(type):
+        pass
+
+    class A:
+        class B: pass
+
+    expected = 'test_add_metaclass_nested.<locals>.A.B'
+
+    assert A.B.__qualname__ == expected
+
+    class A:
+        @six.add_metaclass(Meta)
+        class B: pass
+
+    assert A.B.__qualname__ == expected
+
+
 @py.test.mark.skipif("sys.version_info[:2] < (2, 7) or sys.version_info[:2] in ((3, 0), (3, 1))")
 def test_assertCountEqual():
     class TestAssertCountEqual(unittest.TestCase):