tests: Verify empty observation_direction property

Author: l0b0

tests/extensions/test_sar.py

@@ -1,9 +1,12 @@
 """Tests for pystac.extensions.sar."""
 
 import datetime
+from random import choice
 from typing import List
 import unittest
 
+from string import ascii_letters
+
 import pystac
 from pystac.extensions import sar
 from pystac.extensions.sar import SarExtension
@@ -180,6 +183,16 @@ def test_asset_ext_add_to(self) -> None:
 
         self.assertIn(SarExtension.get_schema_uri(), item.stac_extensions)
 
+    def test_should_return_none_when_observation_direction_is_not_set(self) -> None:
+        extension = SarExtension.ext(self.item)
+        extension.apply(
+            choice(ascii_letters),
+            choice(list(sar.FrequencyBand)),
+            [],
+            choice(ascii_letters),
+        )
+        self.assertIsNone(extension.observation_direction)
+
 
 if __name__ == "__main__":
     unittest.main()