Restrict timezone names for tests

CHANGES.rst

@@ -19,7 +19,7 @@ New features:
 
 Bug fixes:
 
-- ...
+- Restrict timezones tested, see `Issue 763 <https://github.com/collective/icalendar/issues/763>`_
 
 6.1.1 (2025-01-18)
 ------------------

src/icalendar/tests/conftest.py

@@ -1,12 +1,15 @@
 try:
-    from backports import zoneinfo
+    from backports import zoneinfo  # type: ignore  # noqa: PGH003
 except ImportError:
     import zoneinfo
 from typing import Generator
+
 import pytest
 
 import icalendar
 
+from . import timezone_ids
+
 try:
     import pytz
 except ImportError:
@@ -337,3 +340,12 @@ def env_for_doctest(monkeypatch):
 
     monkeypatch.setattr(ZONEINFO, "utc", zoneinfo.ZoneInfo("UTC"))
     return {"print": doctest_print}
+
+
+@pytest.fixture(params=timezone_ids.TZIDS)
+def tzid(request:pytest.FixtureRequest) -> str:
+    """Return a timezone id to be used with pytz or zoneinfo.
+
+    This goes through all the different timezones possible.
+    """
+    return request.param

src/icalendar/tests/test_timezone_identification.py

@@ -1,33 +1,31 @@
-"""Test that we can identify all timezones."""
+"""Test that we can identify all timezones.
 
-import pytest
-try:
-    from zoneinfo import ZoneInfo, available_timezones
-except ImportError:
-    from backports.zoneinfo import ZoneInfo, available_timezones
+Timezones can be removed from ./timezone_ids.py if they make the tests fail:
+Timezone information changes over time and can be dependent on the operating system's
+timezone database (zoneinfo, dateutil) or the package (pytz).
+We want to make sure we can roughly identify most of them.
+"""
 
-from icalendar.timezone import tzids_from_tzinfo, tzid_from_tzinfo
+from icalendar.timezone import tzid_from_tzinfo, tzids_from_tzinfo
+from icalendar.timezone.tzp import TZP
 
-tzids = available_timezones() - {"Factory", "localtime"}
-with_tzid = pytest.mark.parametrize("tzid", tzids)
 
-@with_tzid
-def test_can_identify_zoneinfo(tzid, zoneinfo_only):
+def test_can_identify_zoneinfo(tzid, zoneinfo_only, tzp:TZP):
     """Check that all those zoneinfo timezones can be identified."""
-    assert tzid in tzids_from_tzinfo(ZoneInfo(tzid))
+    assert tzid in tzids_from_tzinfo(tzp.timezone(tzid))
 
-@with_tzid
-def test_can_identify_pytz(tzid, pytz_only):
+
+def test_can_identify_pytz(tzid, pytz_only, tzp:TZP):
     """Check that all those pytz timezones can be identified."""
-    import pytz
-    assert tzid in tzids_from_tzinfo(pytz.timezone(tzid))
+    assert tzid in tzids_from_tzinfo(tzp.timezone(tzid))
+
 
-@with_tzid
 def test_can_identify_dateutil(tzid):
     """Check that all those dateutil timezones can be identified."""
     from dateutil.tz import gettz
     assert tzid in tzids_from_tzinfo(gettz(tzid))
 
+
 def test_utc_is_identified(utc):
     """Test UTC because it is handled in a special way."""
     assert "UTC" in tzids_from_tzinfo(utc)