integration_tests: improve cloud-init.log assertions

[OddBloke]

Proposed Commit Message

integration_tests: improve cloud-init.log assertions

Test Steps

With #592 also in tree, CLOUD_INIT_OS_IMAGE=ubuntu:09768724e1c1 pytest -s tests/integration_tests/bugs will demonstrate the assertion output this modifies. Before this change:

>       assert "WARNING" not in log_content
E       AssertionError: assert 'WARNING' not in '2020-10-01 ...atasources\n'
E         'WARNING' is contained here:
E           2020-10-01 20:49:47,402 - util.py[DEBUG]: Cloud-init v. 20.1-10-g71af48df-0ubuntu5 running 'init-local' at Thu, 01 Oct 2020 20:49:47 +0000. Up 2.06 seconds.
E           2020-10-01 20:49:47,402 - main.py[DEBUG]: No kernel command line url found.
E           2020-10-01 20:49:47,402 - main.py[DEBUG]: Closing stdin.
E           2020-10-01 20:49:47,407 - util.py[DEBUG]: Writing to /var/log/cloud-init.log - ab: [644] 0 bytes
E           2020-10-01 20:49:47,408 - util.py[DEBUG]: Changing the ownership of /var/log/cloud-init.log to 104:4
E           2020-10-01 20:49:47,409 - util.py[DEBUG]: Attempting to remove /var/lib/...
E         
E         ...Full output truncated (439 lines hidden), use '-vv' to show

tests/integration_tests/bugs/test_lp1886531.py:27: AssertionError

whereas after this change:

E       assert "WARNING" not in cloud-init.log string; unexpectedly found on these lines:
E         2020-10-01 20:48:59,040 - util.py[WARNING]: Running module mounts (<module 'cloudinit.config.cc_mounts' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_mounts.py'>) failed

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[TheRealFalcon]

Woah...didn't even know this is something you could override. Nice!

[OddBloke]

Woah...didn't even know this is something you could override. Nice!

Yeah, I knew you could do waves hands custom assertions in pytest, but this is the first time I've actually looked into it at all. It's very neat!

[blackboxsw]

that is so helpful. We could use the same in ua-client tests. Thanks for this!