I never run autogen and make during the tests, this can be done once

after checkout or when modifying the makefiles.

>   make lint
>   make tests

You are missing:

    make storage

Without this, a lot of tests will be skipped or xfailed.

>   make tests-storage
>
> The failing tests are in devicemapper_test.py, outofprocess_test.py and
> qemuimg_test.py.  I have also seen a test failure in nbd_test.py but not
> always.  Is it a problem of the tests or of my environment?

nbd_test.py should be skipped unless you run as root, or have running
supervdsm serving your user.

I usually run the storage tests like this locally on Fedora (35 now):

    make storage
    tox -e storage

Results:

storage/devicemapper_test.py - 5 pass, rest skip
storage/nbd_test.py - 2 pass, rest skip
storage/qemuimg_test.py - 2 skips 
storage/outofprocess_test.py - 3 skips, rest pass 

2350 passed, 161 skipped, 102 deselected, 3 xfailed, 13093 warnings in 134.80s (0:02:14) 

I'll try later using the container.

Nir