Enable testing for datetime in invariance testing

tests/hypothesis_strategies.py

@@ -1,4 +1,5 @@
 from collections import OrderedDict, defaultdict
+from datetime import timedelta, timezone
 
 from cbor2.types import FrozenDict
 from hypothesis import strategies
@@ -7,6 +8,12 @@
 MAX_SIZE = 5
 MAX_LEAVES = 2
 
+# Seconds in timezones get rounded when serialised, so we can only test whole minute
+# timezones for invariance
+timezones = strategies.integers(min_value=-(24 * 60 - 1), max_value=24 * 60 - 1).map(
+ lambda m: timezone(timedelta(minutes=m))
+)
+
 basic_immutable_strategy = strategies.one_of(
  strategies.none(),
  strategies.booleans(),
@@ -16,8 +23,7 @@
  # nan != nan, so we can't test invariance with it
  strategies.floats(allow_nan=False),
  strategies.decimals(allow_nan=False),
- # TODO: fix seconds in timezones
- # strategies.datetimes(timezones=strategies.timezones()),
+ strategies.datetimes(timezones=timezones),
  # TODO: this needs to be fetched from impl fixture instead of imported
  # strategies.just(undefined),
  strategies.fractions(),