pytest should warn about threads kept alive after testing

[fabioz]

Given some code such as:

def test_thread_keeps_process_alive():
    import threading
    import time

    def sleep_forever():
        while True:
            time.sleep(1000)

    threading.Thread(target=sleep_forever).start()

ideally pytest would warn that threads are still running after the test finishes (as the process is still running the ci will fail the build because of a timeout without any signal of what could be the issue).

As a note, the pydev test runner does give such a message, so, that implementation could be borrowed:

https://github.com/fabioz/PyDev.Debugger/blob/master/runfiles.py#L284

[pytestbot]

GitMate.io thinks possibly related issues are #3214 (Pytest hangs when invoked after thread.start()), #1045 (pytest-warnings fails tests since 2.8), #1370 (Print out pytest-warnings?), #253 (pytest should integrate with warnings module), and #3251 (Warnings not captured during test collection).

[RonnyPfannschmidt]

as pytest itself doesnt support threading, a plugin should handle it

[nicoddemus]

Thanks for the suggestion @fabioz,

I agree with @RonnyPfannschmidt, a plugin looks like the correct place for this functionality.

Should be simple as well, the code from PyDev could go into a pytest_unconfigure hook: at that point all tests and fixtures have finished, so no threads should be alive by then.

Using pytest-cookiecutter will also make it very easy to set a repository up.

I'm closing this, but thanks again for the suggestion, we appreciate it!

[lzy017]

Could you tell me how to use pytest-cookiecutter solve the problem that pytest itself doesnt support threading please, thankyou very much @nicoddemus

[RonnyPfannschmidt]

@lzy017 is just a template to get started with making a pytest plugin, its not solving/sorting any of the threading related issues, thats something else

[lzy017]

thnaks could you tell me pytest how to support threading without fixture @RonnyPfannschmidt

[RonnyPfannschmidt]

its not clear to me what you are asking of and i did not investigate the apis needed for debug tooling myself, so you are on your own of you want to tackle this

[nicoddemus]

Hi @lzy017,

Could you tell me how to use pytest-cookiecutter solve the problem that pytest itself doesnt support threading please, thankyou very much @nicoddemus

My suggestion in #3662 (comment) is about writing a new plugin which would check for alive threads during pytest_unconfigure. pytest-cookiecutter makes creating new plugins a breeze.

[blueyed]

btw: #5244 is about pytest not exiting if pdb is still active in some thread.