How to assert a mock was invoked with a specific type rather than instance?

Question

I'm using the latest version of mock and python 2.7.3

I'm building my first flask app and I'm testing some basic middleware to see if flask.abort() happens (and when it does, I assert a method was called with the Unauthorized exception)

    def test_invokes_raise_http_exception_when_apply_blows_up(self):
        start_response = mock.Mock()
        self.sut = BrokenMiddleware(self.app)
        with mock.patch.object(self.sut, 'raise_http_exception') as raise_up:
            self.sut.__call__({}, start_response)
        raise_up.assert_called_once_with(Unauthorized(), start_response)

class BrokenMiddleware(Middleware):

    def apply_middleware(self, environ):
        flask.abort(401)

Here is my production code

class Middleware(object):
    def __call__(self, environ, start_response):                                                                               
        try:
            self.apply_middleware(environ)
        except Exception as e:
            return self.raise_http_exception(e, start_response)

    def raise_http_exception(self, exception, start_response):
        pass

The issue I'm having is that mock fails the assert because the 401 raised is not the same as the one I'm expecting in the assertion itself.

If I only care about the type, not the actual instance how could i rewrite the assertion?

Matthew J Morrison Matthew J Morrison · Accepted Answer · 2012-10-10T14:27:41

You're probably not going to like it, but this is how I've done the same thing in the past:

self.assertIsInstance(raise_up.mock_calls[0][1][0], Unauthorized)

Here is some explanation

>>> print raise_up.mock_calls
[call(Unauthorized())]
>>> print raise_up.mock_calls[0]
call(Unauthorized())
>>> print raise_up.mock_calls[0][1]
(Unauthorized(),)
>>> print type(raise_up.mock_calls[0][1][0])
<type 'Unauthorized'>

How to assert a mock was invoked with a specific type rather than instance?

1 Answers