Question: Hook for subtest start

[mrbean-bremen]

Hi,
I'm a maintainer for pyfakefs and currently trying to make it play nice with pytest-subtests (see this issue).
As pyfakefs patches the filesystem, I have to make sure that it is not active during reporting, so I currently suspend patching in pytest_runtest_logreport and resume it (provided the fixture is still active) in pytest_runtest_call.
This does not work with subtests, as pytest_runtest_logreport is called before each subtest (which suspends patching), but pytest_runtest_call is not, and I failed to find a hook to switch it back on before the next subtest. Is there a possibility (hook or otherwise) to get notified before a subtest is run which I can rely on?

Thanks!

[RonnyPfannschmidt]

currently there is no such hook,

i just took note that the fix for pytest-dev/pyfakefs#904 is incorrect
i recommended a tryfirst hookwrapper as the hookwrapper can undo the suspense in the hook itself

the implementation https://github.com/pytest-dev/pyfakefs/pull/907/files does not use a hookwrapper

a non hookwrapper tryfirst hook will never be invoked before hookwrappers and would always require a extra hack for undoing

[mrbean-bremen]

Thanks @RonnyPfannschmidt, I obviously got that wrong. Will fix this probably tomorrow.

[mrbean-bremen]

I have to admit that I didn't know about hookwrappers - completely overlooked them in the documentation - so I probably just misunderstood that in your suggestion. A hookwrapper is quite useful and exactly what I was looking for, thanks!