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patch.stopall() breaks pytest-mock

See original GitHub issue

I’ve just added pytest and pytest-mock to a legacy project and found that this error was being raised after tests completed.

Traceback (most recent call last):
  File "…/lib/python2.7/site-packages/pytest.py", line 89, in <module>
    raise SystemExit(pytest.main())
  File "…/lib/python2.7/site-packages/_pytest/config/__init__.py", line 80, in main
    return config.hook.pytest_cmdline_main(config=config)
  File "…/lib/python2.7/site-packages/pluggy/hooks.py", line 284, in __call__
    return self._hookexec(self, self.get_hookimpls(), kwargs)
  File "…/lib/python2.7/site-packages/pluggy/manager.py", line 68, in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
  File "…/lib/python2.7/site-packages/pluggy/manager.py", line 62, in <lambda>
    firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
  File "…/lib/python2.7/site-packages/pluggy/callers.py", line 208, in _multicall
    return outcome.get_result()
  File "…/lib/python2.7/site-packages/pluggy/callers.py", line 81, in get_result
    _reraise(*ex)  # noqa
  File "…/lib/python2.7/site-packages/pluggy/callers.py", line 187, in _multicall
    res = hook_impl.function(*args)
  File "…/lib/python2.7/site-packages/_pytest/main.py", line 236, in pytest_cmdline_main
    return wrap_session(config, _main)
  File "…/lib/python2.7/site-packages/_pytest/main.py", line 231, in wrap_session
    config._ensure_unconfigure()
  File "…/lib/python2.7/site-packages/_pytest/config/__init__.py", line 648, in _ensure_unconfigure
    fin()
  File "…/lib/python2.7/site-packages/pytest_mock.py", line 291, in unwrap_assert_methods
    patcher.stop()
  File "…/lib/python2.7/site-packages/mock/mock.py", line 1513, in stop
    return self.__exit__()
  File "…/lib/python2.7/site-packages/mock/mock.py", line 1477, in __exit__
    raise RuntimeError('stop called on unstarted patcher')
RuntimeError: stop called on unstarted patcher

One of the tests in the test suite included a call to patch.stopall(), which seems to have stopped pytest-mock’s mocks and caused this error.