Refs #16455 -- Added test for using opclasses on indexes for multidimensional geometry fields on PostGIS.

tests/gis_tests/gis_migrations/test_operations.py

@@ -19,6 +19,12 @@ except NotImplementedError:
 
 class OperationTestCase(TransactionTestCase):
     available_apps = ['gis_tests.gis_migrations']
+    get_opclass_query = '''
+        SELECT opcname, c.relname FROM pg_opclass AS oc
+        JOIN pg_index as i on oc.oid = ANY(i.indclass)
+        JOIN pg_class as c on c.oid = i.indexrelid
+        WHERE c.relname = %s
+    '''
 
     def tearDown(self):
         # Delete table after testing
@@ -188,6 +194,29 @@ class OperationTests(OperationTestCase):
         if connection.features.supports_raster:
             self.assertSpatialIndexExists('gis_neighborhood', 'rast', raster=True)
 
+    @skipUnlessDBFeature('supports_3d_storage')
+    def test_add_3d_field_opclass(self):
+        if not connection.ops.postgis:
+            self.skipTest('PostGIS-specific test.')
+
+        self.alter_gis_model(
+            migrations.AddField,
+            'Neighborhood',
+            'point3d',
+            field_class=fields.PointField,
+            field_class_kwargs={'dim': 3},
+        )
+        self.assertColumnExists('gis_neighborhood', 'point3d')
+        self.assertSpatialIndexExists('gis_neighborhood', 'point3d')
+
+        with connection.cursor() as cursor:
+            index_name = 'gis_neighborhood_point3d_id'
+            cursor.execute(self.get_opclass_query, [index_name])
+            self.assertEqual(
+                cursor.fetchall(),
+                [('gist_geometry_ops_nd', index_name)],
+            )
+
     @skipUnlessDBFeature('can_alter_geometry_field', 'supports_3d_storage')
     def test_alter_geom_field_dim(self):
         Neighborhood = self.current_state.apps.get_model('gis', 'Neighborhood')