def METHOD_NAME(self):
    self.prepare_data(JWTBearerClientAssertion.CLIENT_AUTH_METHOD)
    rv = self.client.post('/oauth/token', data={
        'grant_type': 'client_credentials',
        'client_assertion_type': JWTBearerClientAssertion.CLIENT_ASSERTION_TYPE
    })
    resp = json.loads(rv.data)
    self.assertEqual(resp['error'], 'invalid_client')