clean up test failures

Author: timgraham

django_mongodb/features.py

@@ -80,12 +80,12 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         "auth_tests.test_views.LoginTest.test_login_session_without_hash_session_key",
         # GenericRelation.value_to_string() assumes integer pk.
         "contenttypes_tests.test_fields.GenericRelationTests.test_value_to_string",
-        # contains with subqueries doesn't work.
+        # contains with Exists() doesn't work:
+        # https://github.com/mongodb-labs/django-mongodb/issues/204
         "model_fields_.test_arrayfield.QueryingTests.test_contains_subquery",
+        # icontains doesn't work on ArrayField:
         # Unsupported conversion from array to string in $convert
         "model_fields_.test_arrayfield.QueryingTests.test_icontains",
-        # None is $in None
-        "model_fields_.test_arrayfield.QueryingTests.test_in_as_F_object",
     }
     # $bitAnd, #bitOr, and $bitXor are new in MongoDB 6.3.
     _django_test_expected_failures_bitwise = {

tests/model_fields_/test_arrayfield.py

@@ -289,10 +289,8 @@ def test_in_subquery(self):
 
     @unittest.expectedFailure
     def test_in_including_F_object(self):
-        # This test asserts that Array objects passed to filters can be
-        # constructed to contain F objects. This currently doesn't work as the
-        # psycopg mogrify method that generates the ARRAY() syntax is
-        # expecting literals, not column references (#27095).
+        # Array objects passed to filters can be constructed to contain
+        # F objects. This doesn't work on PostgreSQL either (#27095).
         self.assertSequenceEqual(
             NullableIntegerArrayModel.objects.filter(field__in=[[models.F("id")]]),
             self.objs[:2],
@@ -301,7 +299,12 @@ def test_in_including_F_object(self):
     def test_in_as_F_object(self):
         self.assertSequenceEqual(
             NullableIntegerArrayModel.objects.filter(field__in=[models.F("field")]),
-            self.objs[:4],
+            # Unlike PostgreSQL, MongoDB returns documents with field=null,
+            # i.e. null is in [null]. It seems okay to leave this alone rather
+            # than filtering out null in all $in queries. Feel free to
+            # reconsider this decision if the behavior is problematic in some
+            # other query.
+            self.objs,
         )
 
     def test_contains(self):