InvocationError when testing via tox but not via pytest called directly

I’ve set up a minimally reproducible example as a repo here. The README explains how I’ve invoked the test using pytest directly and with tox, and I can’t figure out why it doesn’t work with tox.

If I’ve made an obvious error in my tox.ini somewhere, I’d appreciate finding out what to fix. This is the only place in the tox code that prints out the InvocationError without any other information except the command in question (what I’m seeing).

It should also be noted that I can run pytest-qt’s tests with tox just fine. Also, if I comment out the test function’s contents and remove the use of the qtbot fixture, the test runs fine with tox.

[The-Compiler]

Does adding passenv = * under [testenv] change anything? Can you install the pytest-faulthandler plugin and run pytest with -s and see if that gives you anything useful?

edit: My best guess would be that passenv = DISPLAY fixes this

[The-Compiler]

You’ll either need to do that or install pytest-xvfb then.

Unfortunately, Qt simply calls abort() on that error, and pytest’s output capturing can’t show the error to you as the process was just killed.

There’s really not much we can do about this… I wonder if it’d help if pytest-qt disabled the output capturing while creating the QApplication though.