TST: Test missing optional strands don't raise errors

tests/test_manifest_strands.py

@@ -308,3 +308,8 @@ def test_error_raised_if_multiple_datasets_have_same_name(self):
 
         with self.assertRaises(KeyError):
             twine.validate_input_manifest(source=input_manifest)
+
+    def test_missing_optional_manifest_does_not_raise_error(self):
+        """Test that not providing an optional strand doesn't result in a validation error."""
+        twine = Twine(source={"output_manifest": {"datasets": {}, "optional": True}})
+        twine.validate(output_manifest=None)

tests/test_schema_strands.py

@@ -111,6 +111,11 @@ def test_valid_with_extra_values(self):
 
         Twine(source=VALID_SCHEMA_TWINE).validate_configuration_values(source=configuration_valid_with_extra_field)
 
+    def test_missing_optional_values_do_not_raise_error(self):
+        """Test that not providing an optional strand doesn't result in a validation error."""
+        twine = Twine(source={"configuration_values_schema": {"optional": True}})
+        twine.validate(configuration_values=None)
+
 
 if __name__ == "__main__":
     unittest.main()