bpo-30587: Adds signature checking for mock autospec object method calls #1982

claudiubelu · 2017-06-07T11:49:20Z

Mock can accept an spec object / class as argument, making sure that accessing attributes that do not exist in the spec will cause an AttributeError to be raised, but there is no guarantee that the spec's methods signatures are respected in any way. This creates the possibility to have faulty code with passing unit tests and assertions.

Example:

import mock

class Something(object):
    def foo(self, a, b, c, d):
        pass

m = mock.Mock(spec=Something)
m.foo()

Adds the autospec argument to Mock, and its mock_add_spec method.

Passes the spec's attribute with the same name to the child mock (spec-ing the child), if the mock's autospec is True.

Sets _mock_check_sig if the given spec is callable.

Adds unit tests to validate the fact that the autospec method signatures are respected.

https://bugs.python.org/issue30587

the-knights-who-say-ni · 2017-06-07T11:49:22Z

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Mariatta · 2017-06-08T23:48:33Z

Thanks for the PR. This doesn't seem to be a trivial change. Can you please open an issue at https://bugs.python.org, and then reference the issue number in the PR title.

claudiubelu · 2017-06-09T05:02:23Z

Hello. I actually reported a bug for this, but I didn't reference it in the commit message. Will do.

claudiubelu · 2017-11-20T16:09:34Z

@Mariatta Hi, can you take a look again? :)

Mock can accept an spec object / class as argument, making sure that accessing attributes that do not exist in the spec will cause an AttributeError to be raised, but there is no guarantee that the spec's methods signatures are respected in any way. This creates the possibility to have faulty code with passing unittests and assertions. Example: from unittest import mock class Something(object): def foo(self, a, b, c, d): pass m = mock.Mock(spec=Something) m.foo() Adds the autospec argument to Mock, and its mock_add_spec method. Passes the spec's attribute with the same name to the child mock (spec-ing the child), if the mock's autospec is True. Sets _mock_check_sig if the given spec is callable. Adds unit tests to validate the fact that the autospec method signatures are respected.

voidspace · 2019-09-10T09:44:09Z

I'm taking a look at this.

voidspace · 2019-09-10T10:27:41Z

I'd like spec to have signature validation. I don't think the use case for "attribute validation only" (current spec behaviour) is very strong and I'd rather not add new keywords. The mock API is already too complex.

I'll take the existing PR and modify it to use spec instead of adding the new autospec.

ben-reilly · 2019-11-06T23:11:53Z

@voidspace Any status update on this change?

github-actions · 2022-02-19T00:08:48Z