Creating pytz `timezone` always returns `UnknownTimeZoneError`

[lsfischer]

Creating pytz `timezone` always returns `UnknownTimeZoneError`

[mrbean-bremen]

The problem here is that pytz uses time zone information data files inside its package to initialize the time zone, and won't find them in the fake fs.
To fix this, you have to map the timezone files into the fake filesystem, something like this (out of my head):

from pathlib import Path
import pytz

class ExampleTestCase(TestCase):
    def setUp(self):
        self.setUpPyfakefs()
        info_dir = Path(pytz.__file__).parent / "zoneinfo"
        self.fs.add_real_directory(info_dir)

See also this entry in the troubleshooting section of the documentation. It probably would make sense to add this concrete example there.

[mrbean-bremen]

I'm converting this into a discussion issue - it is probably helpful for others.