Refs #31831 -- Added autodector test for unique/index_together on _order field.

tests/migrations/test_autodetector.py

@@ -2151,6 +2151,34 @@ class AutodetectorTests(TestCase):
         )
         self.assertNotIn("_order", [name for name, field in changes['testapp'][0].operations[0].fields])
 
+    def test_add_model_order_with_respect_to_index_foo_together(self):
+        changes = self.get_changes([], [
+            self.book,
+            ModelState('testapp', 'Author', [
+                ('id', models.AutoField(primary_key=True)),
+                ('name', models.CharField(max_length=200)),
+                ('book', models.ForeignKey('otherapp.Book', models.CASCADE)),
+            ], options={
+                'order_with_respect_to': 'book',
+                'index_together': {('name', '_order')},
+                'unique_together': {('id', '_order')},
+            }),
+        ])
+        self.assertNumberMigrations(changes, 'testapp', 1)
+        self.assertOperationTypes(changes, 'testapp', 0, ['CreateModel'])
+        self.assertOperationAttributes(
+            changes,
+            'testapp',
+            0,
+            0,
+            name='Author',
+            options={
+                'order_with_respect_to': 'book',
+                'index_together': {('name', '_order')},
+                'unique_together': {('id', '_order')},
+            },
+        )
+
     def test_alter_model_managers(self):
         """
         Changing the model managers adds a new operation.