Merge pull request #570 from ably/test-error-message

test: Don't assert error messages

test/ably/rest/restchannels_test.py

@@ -87,5 +87,5 @@ async def test_without_permissions(self):
         with pytest.raises(AblyException) as excinfo:
             await ably.channels['test_publish_without_permission'].publish('foo', 'woop')
 
-        assert 'not permitted' in excinfo.value.message
+        assert 40160 == excinfo.value.code
         await ably.close()