'Asserts that the message in a raised exception matches the passed
value.
Args:
expected_exception: Exception class expected to be raised.
expected_message: expected error message string value.
callable_obj: Function to be called.
args: Extra args.
kwargs: Extra kwargs.'

def assertRaisesMessage(self, expected_exception, expected_message, callable_obj=None, *args, **kwargs):

    return six.assertRaisesRegex(self, expected_exception, re.escape(expected_message), callable_obj, *args, **kwargs)
