mocker fixture cannot be used in module scope

[aleGpereira]

If i define a custom fixture like:

@pytest.fixture(scope='module')
def my_fixture(mocker):
// code using mocker

class TestMyModule(object):

def test_one(self, my_fixture):
    // test code

When i run this i get:
ScopeMismatch: You tried to access the 'function' scoped fixture 'mocker' with a 'module' scoped request object, involved factories

I'm i doing something wrong to do something like this? is there some reason why this is not supported?

Thanks.

[nicoddemus]

Hi @aleGpereira,

This is a pytest limitation I'm afraid, mocker is a function-scoped fixture so it cannot be used in higher scopes.

A proposal for a new "invocation-scoped" fixture is proposed in pytest-dev/pytest#1681, but the implementation for that has been pulled back because we encountered some severe problems with the implementation right before a release.

For your module-scope fixture, an alternative is to fallback is the unittest.mock module directly, using a with statement.

Cheers,

[schollii]

A major reason for using mocker is to avoid 4-level deep "with" blocks when patching multiple functions; often using "with" is not very nice. I use the following trick: instead of using nested "with" statements, I define a nest function because I can then define the "mock.patch" as decorators. So instead of:

def test_something(): 
    ...
    with mock.patch(...): 
        with mock.patch(...):
            with mock.patch(...):
                with mock.patch(...):
                     ...

I use this:

def test_something(): 
    ...
    @mock.patch(...)
    @mock.patch(...)
    @mock.patch(...)
    @mock.patch(...)
    def inner_func(_1, _2, _3, _4):
        ...

This is better but the nice thing with mocker, is you don't have to worry about additional call params which you may not even care about (often _1, _2 etc are not used).

So it would be nice to enable mocker to be used in different scopes. How about a mocker_each_func, mocker_each_cls, mocker_each_mod, etc? Just define a few additional mockers, one for each scope, might be simpler than one mocker that adapts.

[matthewatabet]

A simple solution to this could be to provide mocker_session and mocker_module fixtures.

[doandzhiFt]

Greetings! Is there any progress with this one?

[nicoddemus]

Hi @doandzhiFt,

Not really I'm afraid, but I will gladly review and merge a PR that adds mock_session, mock_class and mock_module fixtures. 😁

[scorphus]

Ping, @nicoddemus

[nicoddemus]

Hi @scorphus, sorry for the delay.

I've just merged your patch and will make a release shortly, thanks a lot for the contribution, I appreciate it greatly. 👍

[nicoddemus]

Published in 3.1.0, thanks!

[aleGpereira]

Great work, thanks guys!

[scorphus]

Glad it's useful to you too, @aleGpereira!

Thanks again for the new release, @nicoddemus!

Open source is amazing! Just a few days ago I tried to use mocker in a session-scoped fixture and found this issue. This coming week there's going to be code on production tested by a session-scoped fixture using session_mocker YAY 🎉🙌

[huaxlin]

I had the same problem.

according to this issue, fixed it with module_mocker. 🎉

[pawelad]

It would be good to mention this in the docs - I'll try to open a PR when I have some time.

[pawelad]

It would be good to mention this in the docs - I'll try to open a PR when I have some time.

Actually, it's already in there, I just somehow missed it (twice?):

pytest-mock/docs/usage.rst

Lines 39 to 45 in e023728

	It is also possible to use mocking functionality from fixtures of other scopes using
	the appropriate fixture:
	* ``class_mocker``
	* ``module_mocker``
	* ``package_mocker``
	* ``session_mocker``