Need a way to specify types for mock objects (e.g. mock.Mock())

[timabbott]

Example test case code here:

if True:
    from pycurl import Curl, version_info
else:
    from mock import Mock
    Curl = Mock()
    version_info = Mock()

Posting this in mypy, since I don't think it's possible to specify a typeshed type for mock.Mock that won't throw an error; e.g. if stubs say mock.Mock is an Any, you get /home/tabbott/foo.py:7: error: Invalid assignment target

Reporting as separate from #1152 since this might be worth solving even if that is not, since most every use of mock.Mock() will have this problem.

[JukkaL]

Here is one way of supporting this:

• Make mock.Mock same as Any in the stubs.
• Allow assigning a value of type Any to an arbitrary target, including to a class or a module.

Another approach would be to special case Mock, but the above idea seems more general and not very problematic.

[timabbott]

Yeah, I think that approach makes a lot of sense.

[kentwongg]

I'm writing unit tests and this is a real nuisance for PEP8 compliance.

example code:

class FactoryHandler:
"""
:param worker:
:type worker:
"""

class TestFactoryHandler
    def test_something(self):
         worker = MagicMock()
         factory = FactoryHandler(worker)

PEP8 Type check will throw a warning saying it expected a type worker but got type magic mock instead.
As far as I know, all I can do is # no inspection the line.

[gvanrossum]

What is "PEP8 Type check"?

Note that we waffled a bit on this -- up till mypy 0.610 there was no typeshed definition for Mock. Then we added one, but we found it was too noisy, and we rolled it back, instead changing it so that we have Mock: Any in mock.pyi.

See also python/typing#567. (Maybe this is the feature Tim was looking for?)

[MatanRubin]

Any updates on this? Running Mypy on any test that involves mocks is painful...

[gvanrossum]

If you want help, please post a full example of what you’re experiencing.

On Thu, Apr 11, 2019 at 8:17 AM Matan Rubin ***@***.***> wrote: Any updates on this? Running Mypy on any test that involves mocks is painful... — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#1188 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACwrMmqE8aOI-a5a_BNeNzvQaXyKSJ8tks5vf1IegaJpZM4HOzDL> .

-- --Guido (mobile)

[MatanRubin]

@gvanrossum, after re-examining the behavior I'm experiencing, I think it's related to this issue but not exactly the same.

Opened a separate issue to track what I'm seeing: #6713

[bandophahita]

Would/Could using Protocols work to annotate mocked objects?

class MyMockedObjectProtocol(MockProtocol, MyObjectProtocol, Protocol):
    ...

mymock: MyMockedObjectProtocol = Mock()