Use type alias for temporal intervals (#744)

* Use type alias for temporal intervals

* Fix TemporalIntervalsLike type alias

* Add CHANGELOG entry for #744

CHANGELOG.md

@@ -15,6 +15,7 @@
 
 - Self links no longer included in Items for "relative published" catalogs ([#725](https://github.com/stac-utils/pystac/pull/725))
 - Adding New and Custom Extensions tutorial now up-to-date with new extensions API ([#724](https://github.com/stac-utils/pystac/pull/724))
+- Type errors when initializing `TemporalExtent` using a list of `datetime` objects ([#744](https://github.com/stac-utils/pystac/pull/744))
 
 ### Deprecated
 

pystac/collection.py

@@ -37,6 +37,10 @@
     from pystac.provider import Provider as Provider_Type
 
 T = TypeVar("T")
+TemporalIntervals = Union[List[List[datetime]], List[List[Optional[datetime]]]]
+TemporalIntervalsLike = Union[
+    TemporalIntervals, List[datetime], List[Optional[datetime]]
+]
 
 
 class SpatialExtent:
@@ -176,7 +180,7 @@ class TemporalExtent:
         Datetimes are required to be in UTC.
     """
 
-    intervals: List[List[Optional[datetime]]]
+    intervals: TemporalIntervals
     """A list of two datetimes wrapped in a list,
     representing the temporal extent of a Collection. Open date ranges are
     represented by either the start (the first element of the interval) or the
@@ -188,16 +192,16 @@ class TemporalExtent:
 
     def __init__(
         self,
-        intervals: Union[List[List[Optional[datetime]]], List[Optional[datetime]]],
+        intervals: TemporalIntervals,
         extra_fields: Optional[Dict[str, Any]] = None,
     ):
         # A common mistake is to pass in a single interval instead of a
         # list of intervals. Account for this by transforming the input
         # in that case.
         if isinstance(intervals, list) and isinstance(intervals[0], datetime):
-            self.intervals = [cast(List[Optional[datetime]], intervals)]
+            self.intervals = intervals
         else:
-            self.intervals = cast(List[List[Optional[datetime]]], intervals)
+            self.intervals = intervals
 
         self.extra_fields = extra_fields or {}
 

tests/test_collection.py

@@ -18,7 +18,7 @@
     CatalogType,
     Provider,
 )
-from pystac.utils import datetime_to_str, get_required
+from pystac.utils import datetime_to_str, get_required, str_to_datetime
 from tests.utils import TestCases, ARBITRARY_GEOM, ARBITRARY_BBOX
 
 TEST_DATETIME = datetime(2020, 3, 14, 16, 32)
@@ -263,6 +263,14 @@ class ExtentTest(unittest.TestCase):
     def setUp(self) -> None:
         self.maxDiff = None
 
+    def test_temporal_extent_init_typing(self) -> None:
+        # This test exists purely to test the typing of the intervals argument to
+        # TemporalExtent
+        start_datetime = str_to_datetime("2022-01-01T00:00:00Z")
+        end_datetime = str_to_datetime("2022-01-31T23:59:59Z")
+
+        _ = TemporalExtent([[start_datetime, end_datetime]])
+
     def test_spatial_allows_single_bbox(self) -> None:
         temporal_extent = TemporalExtent(intervals=[[TEST_DATETIME, None]])