Fix isfuture() to support Mock(asyncio.Future)

Fixes python#454.

Author: 1st1

asyncio/futures.py

@@ -117,7 +117,7 @@ def isfuture(obj):
     itself as duck-type compatible by setting _asyncio_future_blocking.
     See comment in Future for more details.
     """
-    return (hasattr(type(obj), '_asyncio_future_blocking') and
+    return (hasattr(obj.__class__, '_asyncio_future_blocking') and
             obj._asyncio_future_blocking is not None)
 
 

tests/test_futures.py

@@ -113,8 +113,13 @@ def __init__(self):
 
         self.assertFalse(asyncio.isfuture(1))
         self.assertFalse(asyncio.isfuture(asyncio.Future))
+
+        # As `isinstance(Mock(), Future)` returns `False`
         self.assertFalse(asyncio.isfuture(mock.Mock()))
 
+        # As `isinstance(Mock(Future), Future)` returns `True`
+        self.assertTrue(asyncio.isfuture(mock.Mock(asyncio.Future)))
+
         f = asyncio.Future(loop=self.loop)
         self.assertTrue(asyncio.isfuture(f))
         f.cancel()