Add a default msg to show the response content.

[jackton1]

This seems like an issue with using assertResponseNoErrors and assertResponseHasErrors

Which doesn't include any errors specific to the response and currently just shows.

    self.assertNotIn("errors", list(content.keys()))
AssertionError: 'errors' unexpectedly found in ['errors', 'data']

Expected:

self.assertNotIn("errors", list(content.keys()), content)
AssertionError: 'errors' unexpectedly found in ['errors', 'data'] : {'errors': [{'message': "mutate() missing 1 required positional argument: 'info'", 'locations': [{'line': 3, 'column': 17}], 'path': ['eventCancel']}], 'data': None}

@artofhuman @syrusakbary

[zbyte64]

👍 Nice polish

[tcleonard]

Nice