pytest：使用假设时的monkeypatch

问题描述

在单元测试中，我使用monkeypatch来更改dict中的条目。

from hypothesis import given,strategies


test_dict = {"first": "text1","second": "text2"}


@given(val=strategies.text())
def test_monkeypath(monkeypatch,val):
    monkeypatch.setitem(test_dict,"second",val)

    assert isinstance(test_dict["second"],str)

测试通过，但是用pytest执行以下测试代码时，我得到警告。

=================================================================================================================== warnings summary ====================================================================================================================
.PyCharm2019.2/config/scratches/hypothesis_monkeypatch.py::test_monkeypath
  c:\users\d292498\appdata\local\conda\conda\envs\pybt\lib\site-packages\hypothesis\extra\pytestplugin.py:172: HypothesisDeprecationWarning: .PyCharm2019.2/config/scratches/hypothesis_monkeypatch.py::test_monkeypath uses the 'monkeypatch' fixture,wh
ich is reset between function calls but not between test cases generated by `@given(...)`.  You can change it to a module- or session-scoped fixture if it is safe to reuse; if not we recommend using a context manager inside your test function.  See h
ttps://docs.pytest.org/en/latest/fixture.html#sharing-test-data for details on fixture scope.
    note_deprecation(

-- Docs: https://docs.pytest.org/en/stable/warnings.html
============================================================================================================= 1 passed,1 warning in 0.30s ==============================================================================================================

这是否意味着dict的值将只更改一次，而不管hypothesis会生成多少个测试用例？
我不确定在这种情况下如何使用上下文管理器。有人可以指出我正确的方向吗？

解决方法

您的问题是，对于所有测试调用，该字典仅被修补一次，并且假设向您发出警告。如果您在monkeypatch.setitem行之前有任何逻辑，那就太糟糕了！

您可以通过using monkeypatch directly来解决此问题，而不是通过治具：

from hypothesis import given,strategies
from _pytest.monkeypatch import MonkeyPatch


test_dict = {"first": "text1","second": "text2"}


@given(val=strategies.text())
def test_monkeypath(val):
    assert test_dict["second"] == "text2"  # this would fail in your version

    with MonkeyPatch().context() as mp:
        mp.setitem(test_dict,"second",val)
        assert test_dict["second"] == val

    assert test_dict["second"] == "text2"

et voila ，没有警告。

,

使用monkeypatch context manager

@given(val=strategies.text())
def test_monkeypath(monkeypatch,val):
    with monkeypatch.context() as m:
        m.setitem(test_dict,val)

        assert isinstance(test_dict["second"],str)