The NumPy CI tests fail if pytest is bumped from 6.0.2 to 6.1.0. The error message is

pytest.PytestAssertRewriteWarning: Module already imported so cannot be rewritten: hypothesis

See https://travis-ci.org/github/numpy/numpy/jobs/730868650 for an example. Note that NumPy fails on warnings. I also see this warning when running tests locally where it is ignored.

• a detailed description of the bug or problem you are having
• output of pip list from the virtual environment you are using
• pytest and operating system versions
• minimal example if possible