'Tests that PythonOperator will only instantiate if
the python_callable argument is callable.'

def test_python_operator_python_callable_is_callable(self):

    not_callable = {}
    with self.assertRaises(AirflowException):
        PythonOperator(python_callable=not_callable, task_id=u'python_operator', dag=self.dag)
    not_callable = None
    with self.assertRaises(AirflowException):
        PythonOperator(python_callable=not_callable, task_id=u'python_operator', dag=self.dag)
