Update tests/test_utils_typecast.py

tests/test_utils_typecast.py

@@ -31,7 +31,7 @@ def test_downcast_success():
 def test_upcast_success():
     b = Bulldog()
     assert b.snore() == "woooooof"
-    assert not hasattr(d, "speak")
+    assert not hasattr(b, "speak")
     upcast(b, Dog)
     assert b.speak() == "woof"
     assert not hasattr(b, "snore")