Fix unit test.

Author: WaVEV

django_mongodb_backend/query.py

@@ -140,7 +140,7 @@ def _get_reroot_replacements(expressions):
                     # lhs_fields.
                     if hand_side_value.alias != self.table_alias:
                         pos = len(lhs_fields)
-                        lhs_fields.append(expr.lhs.as_mql(compiler, connection))
+                        lhs_fields.append(hand_side_value.as_mql(compiler, connection))
                     else:
                         pos = None
                     columns.append((hand_side_value, pos))

tests/queries_/test_mql.py

@@ -173,13 +173,12 @@ def test_push_equality_between_parent_and_child_fields(self):
         query = ctx.captured_queries[0]["sql"]
         self.assertEqual(
             query,
-            "db.queries__order.aggregate([{'$lookup': {'from': "
-            "'queries__orderitem', 'let': {'parent__field__0': '$_id', "
-            "'parent__field__1': '$queries__orderitem.status'}, 'pipeline': "
-            "[{'$match': {'$expr': {'$and': [{'$eq': ['$$parent__field__0', "
-            "'$order_id']}, {'$eq': ['$status', '$$parent__field__1']}]}}}], "
-            "'as': 'queries__orderitem'}}, {'$unwind': "
-            "'$queries__orderitem'}, {'$match': {'$expr': {'$eq': "
-            "['$queries__orderitem.status', '$_id']}}}, {'$addFields': "
-            "{'_id': '$_id'}}, {'$sort': SON([('_id', 1)])}])",
+            "db.queries__order.aggregate([{'$lookup': {'from': 'queries__orderitem', "
+            "'let': {'parent__field__0': '$_id', 'parent__field__1': '$_id'}, "
+            "'pipeline': [{'$match': {'$expr': {'$and': [{'$eq': "
+            "['$$parent__field__0', '$order_id']}, {'$eq': ['$status', "
+            "'$$parent__field__1']}]}}}], 'as': 'queries__orderitem'}}, "
+            "{'$unwind': '$queries__orderitem'}, {'$match': {'$expr': "
+            "{'$eq': ['$queries__orderitem.status', '$_id']}}}, "
+            "{'$addFields': {'_id': '$_id'}}, {'$sort': SON([('_id', 1)])}])",
         )