Set timeout for both test function only and test function + all fixture setup and teardown

It would be nice if it was possible to set a separate timeout for calling the function instead of just setting that the timeout applies only to the function. Currently I can set timeout_func_only = true in pyproject.toml, but that means that all timeouts apply only to the test function.

Concretely, The problem is that I have two kind of timeouts.

I would like to enforce that a selection of tests are fast when fixtures that can be cached are ignored. I currently run those like this:

pytest -m "not slow" tests/ --timeout=10

with timeout_func_only = true in pyproject.toml.

This is to maintain a set (the majority in our case, more than 2k), can be ran quickly (takes less than 40s with caching and pytest-xdist). Each of those tests should take less than 0.1s so a generous timeout of 10s seems appropriate. Only setting a session timeout for this run is not as reliable as it can vary widely because of pytest-xdist.

However, when running all tests in a CI runner, I need to set an appropriate large timeout (roughly 300s) for each test in order to avoid that a hanging test racks up billable minutes. A session timeout works, but needs to be set to an even larger timeout in order to avoid spurious fails due to variation. For this use case I would like to have timeout_func_only = false as slow fixtures matters for billable minutes.

Start by reviewing the existing timeout_func_only configuration and the timeout handling for test functions, fixtures, setup, and teardown. Define how separate function-only and full-test timeouts should be configured and verified for both the fast test run and the CI use case.