How to test log output with zope.testrunner?

While pytest makes it very easy to work with log files via the caplog fixture, I was not aware how to test them with zope.testrunner, which is used for almost all Zope repositories.

When I asked during yesterday’s Zope sprint, I got no answer.

But coincidentally, I stumbled upon a broken doctest which… tests the log output of a function!

So… thanks for failing… I guess :-)

You need to setup a log handler, which captures the log messages…

>>> import zope.testing.loggingsupport
>>> handler = zope.testing.loggingsupport.InstalledHandler('ZEO', level=logging.ERROR)

… and then you can inspect the list of log records…

>>> handler.records

Do not forget to clean up afterwards!

>>> handlers.uninstall()  # remove handler(s), and thus stop collecting log records
>>> handlers.clear()  # delete collected log records

update

2021.04.24:

• added missing teardown instructions - thanks to Marius for pointing out!