Exclude some tests by default

I wish to configure pytest such that it excludes some tests by default; but it should be easy to include them again with some command line option. I only found -k, and I have the impression that that allows complex specifications, but am not sure how to go about my specific need…

The exclusion should be part of the source or a config file (it’s permanent – think about very long-running tests which should only be included as conscious choice, certainly never in a build pipeline…).

Bonus question: if that is not possible, how would I use -k to exclude specific tests? Again, I saw hints in the documentation about a way to use not as a keyword, but that doesn’t seem to work for me. I.e., -k "not longrunning" gives an error about not being able to find a file “notrunning”, but does not exclude anything…

Answer

You can use pytest to mark some tests and use -k arg to skip or include them.

For example consider following tests,

import pytest

def test_a():
    assert True

@pytest.mark.never_run
def test_b():
    assert True


def test_c():
    assert True
    
@pytest.mark.never_run
def test_d():
    assert True

you can run pytest like this to run all the tests

pytest

To skip the marked tests you can run pytest like this,

pytest -m "not never_run"

If you want to run the marked tests alone,

pytest -m "never_run"