'Everything callable in the exception module should be renderable.
... except for the base error class (exception.Error), which is not
user-facing.
This test provides a custom message to bypass docstring parsing, which
should be tested separately.'

def test_all_json_renderings(self):

    for cls in [x for x in exception.__dict__.values() if callable(x)]:
        if ((cls is not exception.Error) and isinstance(cls, exception.Error)):
            self.assertValidJsonRendering(cls(message='Overridden.'))
