ERROR: Invalid test-group argument when using with -k something

[dimaqq]

First of all, thank you for much for this package!

It's simple, intuitive, and just the right kind of software :)

One usability issue I have is that I cannot just slap --test-group-count ... onto an existing codebase to parallelise the CI.

I have to guess the right number for the group count.

If there's only 1 test, then count=2, group=2 (typically? always?) errors out with "invalid test-group arg".

One case if it's a new repo, and there are too few tests.

Another case is using test groups and -m or -k selectors together.

It's very easy to end up in a situation where fewer tests are selected than there are groups.

And I'd want to make sure I run every group, because I don't want to accidentally end up with some tests not being run.

[joesdiner]

It appears that removing lines 102 and 103 in pytest-test-groups/pytest_test_groups/init.py should fix the issue, although I didn't actually test it. Since pytest itself doesn't fail it no tests are run, it doesn't seem like pytest-test-groups should cause a failure if no tests are run either. There is already a check in _get_start() to ensure that test-group is less than test-group-count to prevent foot guns.. At the very least I would say there should be an option to disable raising this exception if no tests are collected for a group.