take a detailed look at integration with the monkeypatch fixture

[RonnyPfannschmidt]

[RonnyPfannschmidt]

after some analysis i came to the conclusion that monkeypatch needs to be extended and a mock integration for pytest should never use mock.patch

[nicoddemus]

Hi @RonnyPfannschmidt,

I'm not sure what you mean, can you clarify your request a bit please? How would you like to extend monkeypatch, and what do you mean by mock integration for pytest should never use mock.patch?

[RonnyPfannschmidt]

mock.patch maintains a custom set of own monkey-patches which is completely unaware of pytest

monkeypatch is neither context nest-able, nor can it do partial undo

so for a proper integration monkeypatch needs partial undo

[nicoddemus]

I'm not sure what your overall object is... to integrate pytest-mock into pytest? Unify the implementations? Make pytest-mock use monkeypatch?

While there is overlap, monkeypatch and unittest.mock are not the same. Monkeypatch does simple attribute substitution, replacing attributes and functions, while unittest.mock does that plus it provides a Mock class which you can configure to behave as another class for testing, monitor calls were made to it, etc. pytest-mock is just a convenience around the unittest.mock module for use with pytest (here's the rationale).

[RonnyPfannschmidt]

my basic understanding is that mock.patch deals with monkeypatching mock objects into places so its a monkeypatching mechanism distinct from pytest monkeypatch which means monkeypatch and mock.patch do not integrate

i'm not yet after a implementation unification, but i'd like to have things in place that taking mock support into pytest later on is straightforward and well combined

[nicoddemus]

monkeypatch has an undo method, so implementing support for with statement seems straightforward to implement.

I'm not sure what you mean by which means monkeypatch and mock.patch do not integrate, since I think this works:

m = mock.Mock()
monkeypatch(obj, 'attr', m)

[RonnyPfannschmidt]

but a monkeypatch works very different from a mock.patch - for example monkeypatch lacks selective undo

[nicoddemus]

That's true

[graingert]

@nicoddemus @RonnyPfannschmidt is this still blocking merging pytest-mock into pytest? With pytest 5 dropping support for platforms without unittest.mock it makes a lot of sense to have it built in

[nicoddemus]

@graingert I'm not sure, because now users will have two builtin options, monkeypatch and mocker, which is confusing.

We might think about how to integrate them instead, for example monkeypatch.mock might behave like the current mocker fixture:

def test_foo(monkeypatch):
    monkeypatch.mock.patch('os.remove')

Or we might decide to add patch and patch.object directly to monkeypatch:

def test_foo(monkeypatch):
    monkeypatch.patch('os.remove')

But actually I'm leaning towards leaving outside the core for now.

[graingert]

This to me sounds like tmp_path and tmpdir

On Fri, 5 Jul 2019, 15:26 Bruno Oliveira, [email protected] wrote:

@graingert https://github.com/graingert I'm not sure, because now users will have two builtin options, monkeypatch and mocker, which is confusing.

We might think about how to integrate them instead, for example monkeypatch.mock might behave like the current mocker fixture:

def test_foo(monkeypatch): monkeypatch.mock.patch('os.remove')

Or we might decide to add patch and patch.object directly to monkeypatch:

def test_foo(monkeypatch): monkeypatch.patch('os.remove')

But actually I'm leaning towards leaving outside the core for now.

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[nicoddemus]

IMO they are widely different: while tmp_path and tmpdir both provide the same temporary directory only changing the type of object returned, monkeypatch and mocker provide completely different interfaces and capabilities: monkeypatch only replaces attributes by an equivalent object, while mocker installs a MagicMock object in-place of existing attributes and adds tons of capabilities, including checking how the mock object was called.