Refs #24900 -- Added MigrationLoader test for applying squashed migrations.

1 files changed, 21 insertions, 0 deletions

diff --git a/tests/migrations/test_loader.py b/tests/migrations/test_loader.py
index 3c4f44aa5e..03a98506e3 100644
--- a/tests/migrations/test_loader.py
+++ b/tests/migrations/test_loader.py
@@ -485,6 +485,27 @@ class LoaderTests(TestCase):
         }
         self.assertEqual(plan, expected_plan)
 
+        # Load with nothing applied and migrate to a replaced migration.
+        # Not possible if loader.replace_migrations is True (default).
+        loader.build_graph()
+        msg = "Node ('app1', '3_auto') not a valid node"
+        with self.assertRaisesMessage(NodeNotFoundError, msg):
+            loader.graph.forwards_plan(('app1', '3_auto'))
+        # Possible if loader.replace_migrations is False.
+        loader.replace_migrations = False
+        loader.build_graph()
+        plan = set(loader.graph.forwards_plan(('app1', '3_auto')))
+        plan = plan - loader.applied_migrations.keys()
+        expected_plan = {
+            ('app1', '1_auto'),
+            ('app2', '1_auto'),
+            ('app2', '2_auto'),
+            ('app1', '2_auto'),
+            ('app1', '3_auto'),
+        }
+        self.assertEqual(plan, expected_plan)
+        loader.replace_migrations = True
+
         # Fake-apply a few from app1: unsquashes migration in app1.
         self.record_applied(recorder, 'app1', '1_auto')
         self.record_applied(recorder, 'app1', '2_auto')