There is no /dev/full device on OpenBSD. If you run the 2.7 regress tests as root on OpenBSD, a /dev/full regular file will be created and the "test_write_full" test will fail. (because the subsequent write will succeed in writing to the /dev/full regular file).

To fix, change the test to check that /dev/full exists and is a character device.

Patch attached.

I would prefer a decorator checking if a device exists, something like:

@requires_character_device('/dev/full')

It would always skip on Windows. Implement it in test_support.py.

We will merge any fix decided by the python team when it's committed. In the meantime may commit our fix on OpenBSD to solve the problem in the short term as it seems no one has time to go further right now.

If it's not needed in other places, I think the proposed patch might be OK (assuming it works fine on other platforms).

The patch is against test_file2k.py which I can't find in my default cpython setup.  If this was removed from (say) Python 3.0 how do I check for that?

I tried to grep on 3.x for this test but it looks like it's been removed there, so this issue only affects 2.7.

New changeset 354c3b65e245 by Serhiy Storchaka in branch '2.7':
Issue #21934: test_file2k no longer create regular file /dev/full on OpenBSD
https://hg.python.org/cpython/rev/354c3b65e245

Why the complication? You could just use open mode "r+".

This was my first idea. But this would be different test. The behavior of files opened with "w" and "r+" modes can be different.