Is there an easy way to disable thread parallelism for tests in one file?

[yurivict]

I have a file with several dozen test_xx functions.

They appear to be run in parallel by PyTest, and since one underlying library isn't thread safe - these tests fail intermittently.

One way to fix this is to add thread locking into each of test_xx procedures, but this would be a lot of changes.

Is there a way to set an option instructing PyTest to run these tests sequentially?

[The-Compiler]

pytest doesn't run anything in parallel. There's the pytest-xdist plugin that allows doing so, but that uses processes and not threads.

[mandras73]

take a look on the docs here
you may use --dist loadgroup
and set test a unique group marker if you would like to execute that one in sequential
example:

@pytest.mark.xdist_group(name="group1")
def test1():
    pass

def test2():
    pass

def test3():
    pass

Results: test2 and test3 run parallel, test1 runs sequential (in a separated group)