How to auto-run an external program after Pytest completes execution?

[jeffwright13]

I've written a Pytest plugin that marks up sections of the output for use by an external program after the test run is over. How can I get Pytest to automatically invoke the external program after it is done?

For this use case, I want to run Pytest with my plugin's fold option, and then have it launch my TUI code (which is written in Python) after it has completed its test run. Any ideas?

[nicoddemus]

Hi @jeffwright13,

Perhaps pytest_sesssionfinish is what you are looking for?

[jeffwright13]

I'll look into it

[jeffwright13]

I added the following code to my plugin.py:

@pytest.hookimpl(trylast=True)
def pytest_sessionfinish(session: Session):
    subprocess.run(
        ["python", "/Users/jwr003/coding/pytest-fold/pytest_fold/tui.py"]
    )

The program seems to launch, but unfortunately it causes the terminal to corrupt and there is a bunch of error code spit to the screen:

Traceback (most recent call last):
File "/Users/jwr003/coding/pytest-fold/pytest_fold/tui.py", line 187, in <module> main()
File "/Users/jwr003/coding/pytest-fold/pytest_fold/tui.py", line 180, in main Screen.wrapper(demo, catch_interrupt=True, arguments=[last_scene])
File "/Users/jwr003/coding/pytest-fold/venv/lib/python3.9/site-packages/asciimatics/screen.py", line 1386, in wrapper screen = Screen.open(height,
File "/Users/jwr003/coding/pytest-fold/venv/lib/python3.9/site-packages/asciimatics/screen.py", line 1355, in open screen = _CursesScreen(stdscr, height,
File "/Users/jwr003/coding/pytest-fold/venv/lib/python3.9/site-packages/asciimatics/screen.py", line 2354, in __init__ tbs = termios.tcgetattr(sys.stdin)[6][termios.VERASE]
termios.error: (19, 'Operation not supported by device') %

It's also clear that despite the claim in the docs that pytest_sessionfinish is "Called after whole test run finished, right before returning the exit status to the system" - there is a lot of other code called after that, because when I set a break point and follow it into a stub subprocess, it returns and then runs dozens of lines of other code.

Anyway, I'll keep digging.

[nicoddemus]

It's also clear that despite the claim in the docs that pytest_sessionfinish is "Called after whole test run finished, right before returning the exit status to the system" - there is a lot of other code called after that

That's expected: it is a hook, so it will invoke all other pytest_sessionfinish hooks in the system (internals and plugins). Those hooks can run anything, plus there's the code involved in the hook machinery itself (pluggy).

[jeffwright13]

Cool, thanks - I figured it was something like that. Looks like I have some learning to do about terminal handling...

[jeffwright13]

I ended up just calling my own method at the end of the whole test run (end of pytest_unconfigure), which makes a subprocess call to my TUI code. For now I seem to have solved the problem. Thanks for your input everyone. :-)