expand test_xerbla_override to allow debugging

[bnavigator]

Be more verbose if the test fails. It could fail because of xerbla not being overridden or because the import of the wrapper library failed.

[repagh]

Yes, it now works fine. I only get errors when running from within the Slycot folder; maybe that was the problem all along.

Slycot repa$ pytest --pyargs slycot

From the result:

input = None, capture_output = False, timeout = None, check = True
popenargs = (['/Users/repa/anaconda3/envs/test-slycot/bin/python', '-c', '\nfrom slycot._wrapper import ab08nd\n# equil=\'X\' is invalid\nout = ab08nd(1, 1, 1, [1], [1], [1], [1], equil=\'X\')\nprint("INFO={}".format(out[-1]))\n'],)
kwargs = {'stderr': -2, 'stdout': -1, 'universal_newlines': True}, process = <subprocess.Popen object at 0x1177f0ad0>
stdout = 'Traceback (most recent call last):\n  File "<string>", line 2, in <module>\n  File "/Users/repa/control/src/Slycot/sl...er\nImportError: cannot import name \'_wrapper\' from \'slycot\' (/Users/repa/control/src/Slycot/slycot/__init__.py)\n'
stderr = None, retcode = 1

The other tests all work, so this seems to be due to the fact that the subprocess code is executed in the current folder, where it finds a slycot sub-folder, complete with init.py but without wrapper.

[bnavigator]

Should be able to run from source folder again

[repagh]

Perfect, good solution