from django.apps.registry import apps as global_apps from django.db import connection from django.db.migrations.exceptions import InvalidMigrationPlan from django.db.migrations.executor import MigrationExecutor from django.db.migrations.graph import MigrationGraph from django.db.migrations.recorder import MigrationRecorder from django.db.utils import DatabaseError from django.test import TestCase, modify_settings, override_settings from .test_base import MigrationTestBase @modify_settings(INSTALLED_APPS={'append': 'migrations2'}) class ExecutorTests(MigrationTestBase): """ Tests the migration executor (full end-to-end running). Bear in mind that if these are failing you should fix the other test failures first, as they may be propagating into here. """ available_apps = ["migrations", "migrations2", "django.contrib.auth", "django.contrib.contenttypes"] @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"}) def test_run(self): """ Tests running a simple set of migrations. """ executor = MigrationExecutor(connection) # Let's look at the plan first and make sure it's up to scratch plan = executor.migration_plan([("migrations", "0002_second")]) self.assertEqual( plan, [ (executor.loader.graph.nodes["migrations", "0001_initial"], False), (executor.loader.graph.nodes["migrations", "0002_second"], False), ], ) # Were the tables there before? self.assertTableNotExists("migrations_author") self.assertTableNotExists("migrations_book") # Alright, let's try running it executor.migrate([("migrations", "0002_second")]) # Are the tables there now? self.assertTableExists("migrations_author") self.assertTableExists("migrations_book") # Rebuild the graph to reflect the new DB state executor.loader.build_graph() # Alright, let's undo what we did plan = executor.migration_plan([("migrations", None)]) self.assertEqual( plan, [ (executor.loader.graph.nodes["migrations", "0002_second"], True), (executor.loader.graph.nodes["migrations", "0001_initial"], True), ], ) executor.migrate([("migrations", None)]) # Are the tables gone? self.assertTableNotExists("migrations_author") self.assertTableNotExists("migrations_book") @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_squashed"}) def test_run_with_squashed(self): """ Tests running a squashed migration from zero (should ignore what it replaces) """ executor = MigrationExecutor(connection) # Check our leaf node is the squashed one leaves = [key for key in executor.loader.graph.leaf_nodes() if key[0] == "migrations"] self.assertEqual(leaves, [("migrations", "0001_squashed_0002")]) # Check the plan plan = executor.migration_plan([("migrations", "0001_squashed_0002")]) self.assertEqual( plan, [ (executor.loader.graph.nodes["migrations", "0001_squashed_0002"], False), ], ) # Were the tables there before? self.assertTableNotExists("migrations_author") self.assertTableNotExists("migrations_book") # Alright, let's try running it executor.migrate([("migrations", "0001_squashed_0002")]) # Are the tables there now? self.assertTableExists("migrations_author") self.assertTableExists("migrations_book") # Rebuild the graph to reflect the new DB state executor.loader.build_graph() # Alright, let's undo what we did. Should also just use squashed. plan = executor.migration_plan([("migrations", None)]) self.assertEqual( plan, [ (executor.loader.graph.nodes["migrations", "0001_squashed_0002"], True), ], ) executor.migrate([("migrations", None)]) # Are the tables gone? self.assertTableNotExists("migrations_author") self.assertTableNotExists("migrations_book") @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_non_atomic"}) def test_non_atomic_migration(self): """ Applying a non-atomic migration works as expected. """ executor = MigrationExecutor(connection) with self.assertRaisesMessage(RuntimeError, "Abort migration"): executor.migrate([("migrations", "0001_initial")]) self.assertTableExists("migrations_publisher") migrations_apps = executor.loader.project_state(("migrations", "0001_initial")).apps Publisher = migrations_apps.get_model("migrations", "Publisher") self.assertTrue(Publisher.objects.exists()) self.assertTableNotExists("migrations_book") @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_atomic_operation"}) def test_atomic_operation_in_non_atomic_migration(self): """ An atomic operation is properly rolled back inside a non-atomic migration. """ executor = MigrationExecutor(connection) with self.assertRaisesMessage(RuntimeError, "Abort migration"): executor.migrate([("migrations", "0001_initial")]) migrations_apps = executor.loader.project_state(("migrations", "0001_initial")).apps Editor = migrations_apps.get_model("migrations", "Editor") self.assertFalse(Editor.objects.exists()) @override_settings(MIGRATION_MODULES={ "migrations": "migrations.test_migrations", "migrations2": "migrations2.test_migrations_2", }) def test_empty_plan(self): """ Tests that re-planning a full migration of a fully-migrated set doesn't perform spurious unmigrations and remigrations. There was previously a bug where the executor just always performed the backwards plan for applied migrations - which even for the most recent migration in an app, might include other, dependent apps, and these were being unmigrated. """ # Make the initial plan, check it executor = MigrationExecutor(connection) plan = executor.migration_plan([ ("migrations", "0002_second"), ("migrations2", "0001_initial"), ]) self.assertEqual( plan, [ (executor.loader.graph.nodes["migrations", "0001_initial"], False), (executor.loader.graph.nodes["migrations", "0002_second"], False), (executor.loader.graph.nodes["migrations2", "0001_initial"], False), ], ) # Fake-apply all migrations executor.migrate([ ("migrations", "0002_second"), ("migrations2", "0001_initial") ], fake=True) # Rebuild the graph to reflect the new DB state executor.loader.build_graph() # Now plan a second time and make sure it's empty plan = executor.migration_plan([ ("migrations", "0002_second"), ("migrations2", "0001_initial"), ]) self.assertEqual(plan, []) # The resulting state should include applied migrations. state = executor.migrate([ ("migrations", "0002_second"), ("migrations2", "0001_initial"), ]) self.assertIn(('migrations', 'book'), state.models) self.assertIn(('migrations', 'author'), state.models) self.assertIn(('migrations2', 'otherauthor'), state.models) # Erase all the fake records executor.recorder.record_unapplied("migrations2", "0001_initial") executor.recorder.record_unapplied("migrations", "0002_second") executor.recorder.record_unapplied("migrations", "0001_initial") @override_settings(MIGRATION_MODULES={ "migrations": "migrations.test_migrations", "migrations2": "migrations2.test_migrations_2_no_deps", }) def test_mixed_plan_not_supported(self): """ Although the MigrationExecutor interfaces allows for mixed migration plans (combined forwards and backwards migrations) this is not supported. """ # Prepare for mixed plan executor = MigrationExecutor(connection) plan = executor.migration_plan([("migrations", "0002_second")]) self.assertEqual( plan, [ (executor.loader.graph.nodes["migrations", "0001_initial"], False), (executor.loader.graph.nodes["migrations", "0002_second"], False), ], ) executor.migrate(None, plan) # Rebuild the graph to reflect the new DB state executor.loader.build_graph() self.assertIn(('migrations', '0001_initial'), executor.loader.applied_migrations) self.assertIn(('migrations', '0002_second'), executor.loader.applied_migrations) self.assertNotIn(('migrations2', '0001_initial'), executor.loader.applied_migrations) # Generate mixed plan plan = executor.migration_plan([ ("migrations", None), ("migrations2", "0001_initial"), ]) msg = ( 'Migration plans with both forwards and backwards migrations are ' 'not supported. Please split your migration process into separate ' 'plans of only forwards OR backwards migrations.' ) with self.assertRaisesMessage(InvalidMigrationPlan, msg) as cm: executor.migrate(None, plan) self.assertEqual( cm.exception.args[1], [ (executor.loader.graph.nodes["migrations", "0002_second"], True), (executor.loader.graph.nodes["migrations", "0001_initial"], True), (executor.loader.graph.nodes["migrations2", "0001_initial"], False), ], ) # Rebuild the graph to reflect the new DB state executor.loader.build_graph() executor.migrate([ ("migrations", None), ("migrations2", None), ]) # Are the tables gone? self.assertTableNotExists("migrations_author") self.assertTableNotExists("migrations_book") self.assertTableNotExists("migrations2_otherauthor") @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"}) def test_soft_apply(self): """ Tests detection of initial migrations already having been applied. """ state = {"faked": None} def fake_storer(phase, migration=None, fake=None): state["faked"] = fake executor = MigrationExecutor(connection, progress_callback=fake_storer) # Were the tables there before? self.assertTableNotExists("migrations_author") self.assertTableNotExists("migrations_tribble") # Run it normally self.assertEqual( executor.migration_plan([("migrations", "0001_initial")]), [ (executor.loader.graph.nodes["migrations", "0001_initial"], False), ], ) executor.migrate([("migrations", "0001_initial")]) # Are the tables there now? self.assertTableExists("migrations_author") self.assertTableExists("migrations_tribble") # We shouldn't have faked that one self.assertIs(state["faked"], False) # Rebuild the graph to reflect the new DB state executor.loader.build_graph() # Fake-reverse that executor.migrate([("migrations", None)], fake=True) # Are the tables still there? self.assertTableExists("migrations_author") self.assertTableExists("migrations_tribble") # Make sure that was faked self.assertIs(state["faked"], True) # Finally, migrate forwards; this should fake-apply our initial migration executor.loader.build_graph() self.assertEqual( executor.migration_plan([("migrations", "0001_initial")]), [ (executor.loader.graph.nodes["migrations", "0001_initial"], False), ], ) # Applying the migration should raise a database level error # because we haven't given the --fake-initial option with self.assertRaises(DatabaseError): executor.migrate([("migrations", "0001_initial")]) # Reset the faked state state = {"faked": None} # Allow faking of initial CreateModel operations executor.migrate([("migrations", "0001_initial")], fake_initial=True) self.assertIs(state["faked"], True) # And migrate back to clean up the database executor.loader.build_graph() executor.migrate([("migrations", None)]) self.assertTableNotExists("migrations_author") self.assertTableNotExists("migrations_tribble") @override_settings( MIGRATION_MODULES={ "migrations": "migrations.test_migrations_custom_user", "django.contrib.auth": "django.contrib.auth.migrations", }, AUTH_USER_MODEL="migrations.Author", ) def test_custom_user(self): """ Regression test for #22325 - references to a custom user model defined in the same app are not resolved correctly. """ executor = MigrationExecutor(connection) self.assertTableNotExists("migrations_author") self.assertTableNotExists("migrations_tribble") # Migrate forwards executor.migrate([("migrations", "0001_initial")]) self.assertTableExists("migrations_author") self.assertTableExists("migrations_tribble") # Make sure the soft-application detection works (#23093) # Change table_names to not return auth_user during this as # it wouldn't be there in a normal run, and ensure migrations.Author # exists in the global app registry temporarily. old_table_names = connection.introspection.table_names connection.introspection.table_names = lambda c: [x for x in old_table_names(c) if x != "auth_user"] migrations_apps = executor.loader.project_state(("migrations", "0001_initial")).apps global_apps.get_app_config("migrations").models["author"] = migrations_apps.get_model("migrations", "author") try: migration = executor.loader.get_migration("auth", "0001_initial") self.assertIs(executor.detect_soft_applied(None, migration)[0], True) finally: connection.introspection.table_names = old_table_names del global_apps.get_app_config("migrations").models["author"] # And migrate back to clean up the database executor.loader.build_graph() executor.migrate([("migrations", None)]) self.assertTableNotExists("migrations_author") self.assertTableNotExists("migrations_tribble") @override_settings( MIGRATION_MODULES={ "migrations": "migrations.test_add_many_to_many_field_initial", }, ) def test_detect_soft_applied_add_field_manytomanyfield(self): """ executor.detect_soft_applied() detects ManyToManyField tables from an AddField operation. This checks the case of AddField in a migration with other operations (0001) and the case of AddField in its own migration (0002). """ tables = [ # from 0001 "migrations_project", "migrations_task", "migrations_project_tasks", # from 0002 "migrations_task_projects", ] executor = MigrationExecutor(connection) # Create the tables for 0001 but make it look like the migration hasn't # been applied. executor.migrate([("migrations", "0001_initial")]) executor.migrate([("migrations", None)], fake=True) for table in tables[:3]: self.assertTableExists(table) # Table detection sees 0001 is applied but not 0002. migration = executor.loader.get_migration("migrations", "0001_initial") self.assertIs(executor.detect_soft_applied(None, migration)[0], True) migration = executor.loader.get_migration("migrations", "0002_initial") self.assertIs(executor.detect_soft_applied(None, migration)[0], False) # Create the tables for both migrations but make it look like neither # has been applied. executor.loader.build_graph() executor.migrate([("migrations", "0001_initial")], fake=True) executor.migrate([("migrations", "0002_initial")]) executor.loader.build_graph() executor.migrate([("migrations", None)], fake=True) # Table detection sees 0002 is applied. migration = executor.loader.get_migration("migrations", "0002_initial") self.assertIs(executor.detect_soft_applied(None, migration)[0], True) # Leave the tables for 0001 except the many-to-many table. That missing # table should cause detect_soft_applied() to return False. with connection.schema_editor() as editor: for table in tables[2:]: editor.execute(editor.sql_delete_table % {"table": table}) migration = executor.loader.get_migration("migrations", "0001_initial") self.assertIs(executor.detect_soft_applied(None, migration)[0], False) # Cleanup by removing the remaining tables. with connection.schema_editor() as editor: for table in tables[:2]: editor.execute(editor.sql_delete_table % {"table": table}) for table in tables: self.assertTableNotExists(table) @override_settings( INSTALLED_APPS=[ "migrations.migrations_test_apps.lookuperror_a", "migrations.migrations_test_apps.lookuperror_b", "migrations.migrations_test_apps.lookuperror_c" ] ) def test_unrelated_model_lookups_forwards(self): """ #24123 - Tests that all models of apps already applied which are unrelated to the first app being applied are part of the initial model state. """ try: executor = MigrationExecutor(connection) self.assertTableNotExists("lookuperror_a_a1") self.assertTableNotExists("lookuperror_b_b1") self.assertTableNotExists("lookuperror_c_c1") executor.migrate([("lookuperror_b", "0003_b3")]) self.assertTableExists("lookuperror_b_b3") # Rebuild the graph to reflect the new DB state executor.loader.build_graph() # Migrate forwards -- This led to a lookup LookupErrors because # lookuperror_b.B2 is already applied executor.migrate([ ("lookuperror_a", "0004_a4"), ("lookuperror_c", "0003_c3"), ]) self.assertTableExists("lookuperror_a_a4") self.assertTableExists("lookuperror_c_c3") # Rebuild the graph to reflect the new DB state executor.loader.build_graph() finally: # Cleanup executor.migrate([ ("lookuperror_a", None), ("lookuperror_b", None), ("lookuperror_c", None), ]) self.assertTableNotExists("lookuperror_a_a1") self.assertTableNotExists("lookuperror_b_b1") self.assertTableNotExists("lookuperror_c_c1") @override_settings( INSTALLED_APPS=[ "migrations.migrations_test_apps.lookuperror_a", "migrations.migrations_test_apps.lookuperror_b", "migrations.migrations_test_apps.lookuperror_c" ] ) def test_unrelated_model_lookups_backwards(self): """ #24123 - Tests that all models of apps being unapplied which are unrelated to the first app being unapplied are part of the initial model state. """ try: executor = MigrationExecutor(connection) self.assertTableNotExists("lookuperror_a_a1") self.assertTableNotExists("lookuperror_b_b1") self.assertTableNotExists("lookuperror_c_c1") executor.migrate([ ("lookuperror_a", "0004_a4"), ("lookuperror_b", "0003_b3"), ("lookuperror_c", "0003_c3"), ]) self.assertTableExists("lookuperror_b_b3") self.assertTableExists("lookuperror_a_a4") self.assertTableExists("lookuperror_c_c3") # Rebuild the graph to reflect the new DB state executor.loader.build_graph() # Migrate backwards -- This led to a lookup LookupErrors because # lookuperror_b.B2 is not in the initial state (unrelated to app c) executor.migrate([("lookuperror_a", None)]) # Rebuild the graph to reflect the new DB state executor.loader.build_graph() finally: # Cleanup executor.migrate([ ("lookuperror_b", None), ("lookuperror_c", None) ]) self.assertTableNotExists("lookuperror_a_a1") self.assertTableNotExists("lookuperror_b_b1") self.assertTableNotExists("lookuperror_c_c1") @override_settings( INSTALLED_APPS=[ 'migrations.migrations_test_apps.mutate_state_a', 'migrations.migrations_test_apps.mutate_state_b', ] ) def test_unrelated_applied_migrations_mutate_state(self): """ #26647 - Unrelated applied migrations should be part of the final state in both directions. """ executor = MigrationExecutor(connection) executor.migrate([ ('mutate_state_b', '0002_add_field'), ]) # Migrate forward. executor.loader.build_graph() state = executor.migrate([ ('mutate_state_a', '0001_initial'), ]) self.assertIn('added', dict(state.models['mutate_state_b', 'b'].fields)) executor.loader.build_graph() # Migrate backward. state = executor.migrate([ ('mutate_state_a', None), ]) self.assertIn('added', dict(state.models['mutate_state_b', 'b'].fields)) @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"}) def test_process_callback(self): """ #24129 - Tests callback process """ call_args_list = [] def callback(*args): call_args_list.append(args) executor = MigrationExecutor(connection, progress_callback=callback) # Were the tables there before? self.assertTableNotExists("migrations_author") self.assertTableNotExists("migrations_tribble") executor.migrate([ ("migrations", "0001_initial"), ("migrations", "0002_second"), ]) # Rebuild the graph to reflect the new DB state executor.loader.build_graph() executor.migrate([ ("migrations", None), ("migrations", None), ]) self.assertTableNotExists("migrations_author") self.assertTableNotExists("migrations_tribble") migrations = executor.loader.graph.nodes expected = [ ("render_start", ), ("render_success", ), ("apply_start", migrations['migrations', '0001_initial'], False), ("apply_success", migrations['migrations', '0001_initial'], False), ("apply_start", migrations['migrations', '0002_second'], False), ("apply_success", migrations['migrations', '0002_second'], False), ("render_start", ), ("render_success", ), ("unapply_start", migrations['migrations', '0002_second'], False), ("unapply_success", migrations['migrations', '0002_second'], False), ("unapply_start", migrations['migrations', '0001_initial'], False), ("unapply_success", migrations['migrations', '0001_initial'], False), ] self.assertEqual(call_args_list, expected) @override_settings( INSTALLED_APPS=[ "migrations.migrations_test_apps.alter_fk.author_app", "migrations.migrations_test_apps.alter_fk.book_app", ] ) def test_alter_id_type_with_fk(self): try: executor = MigrationExecutor(connection) self.assertTableNotExists("author_app_author") self.assertTableNotExists("book_app_book") # Apply initial migrations executor.migrate([ ("author_app", "0001_initial"), ("book_app", "0001_initial"), ]) self.assertTableExists("author_app_author") self.assertTableExists("book_app_book") # Rebuild the graph to reflect the new DB state executor.loader.build_graph() # Apply PK type alteration executor.migrate([("author_app", "0002_alter_id")]) # Rebuild the graph to reflect the new DB state executor.loader.build_graph() finally: # We can't simply unapply the migrations here because there is no # implicit cast from VARCHAR to INT on the database level. with connection.schema_editor() as editor: editor.execute(editor.sql_delete_table % {"table": "book_app_book"}) editor.execute(editor.sql_delete_table % {"table": "author_app_author"}) self.assertTableNotExists("author_app_author") self.assertTableNotExists("book_app_book") @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_squashed"}) def test_apply_all_replaced_marks_replacement_as_applied(self): """ Applying all replaced migrations marks replacement as applied (#24628). """ recorder = MigrationRecorder(connection) # Place the database in a state where the replaced migrations are # partially applied: 0001 is applied, 0002 is not. recorder.record_applied("migrations", "0001_initial") executor = MigrationExecutor(connection) # Use fake because we don't actually have the first migration # applied, so the second will fail. And there's no need to actually # create/modify tables here, we're just testing the # MigrationRecord, which works the same with or without fake. executor.migrate([("migrations", "0002_second")], fake=True) # Because we've now applied 0001 and 0002 both, their squashed # replacement should be marked as applied. self.assertIn( ("migrations", "0001_squashed_0002"), recorder.applied_migrations(), ) @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_squashed"}) def test_migrate_marks_replacement_applied_even_if_it_did_nothing(self): """ A new squash migration will be marked as applied even if all its replaced migrations were previously already applied (#24628). """ recorder = MigrationRecorder(connection) # Record all replaced migrations as applied recorder.record_applied("migrations", "0001_initial") recorder.record_applied("migrations", "0002_second") executor = MigrationExecutor(connection) executor.migrate([("migrations", "0001_squashed_0002")]) # Because 0001 and 0002 are both applied, even though this migrate run # didn't apply anything new, their squashed replacement should be # marked as applied. self.assertIn( ("migrations", "0001_squashed_0002"), recorder.applied_migrations(), ) class FakeLoader(object): def __init__(self, graph, applied): self.graph = graph self.applied_migrations = applied class FakeMigration(object): """Really all we need is any object with a debug-useful repr.""" def __init__(self, name): self.name = name def __repr__(self): return 'M<%s>' % self.name class ExecutorUnitTests(TestCase): """(More) isolated unit tests for executor methods.""" def test_minimize_rollbacks(self): """ Minimize unnecessary rollbacks in connected apps. When you say "./manage.py migrate appA 0001", rather than migrating to just after appA-0001 in the linearized migration plan (which could roll back migrations in other apps that depend on appA 0001, but don't need to be rolled back since we're not rolling back appA 0001), we migrate to just before appA-0002. """ a1_impl = FakeMigration('a1') a1 = ('a', '1') a2_impl = FakeMigration('a2') a2 = ('a', '2') b1_impl = FakeMigration('b1') b1 = ('b', '1') graph = MigrationGraph() graph.add_node(a1, a1_impl) graph.add_node(a2, a2_impl) graph.add_node(b1, b1_impl) graph.add_dependency(None, b1, a1) graph.add_dependency(None, a2, a1) executor = MigrationExecutor(None) executor.loader = FakeLoader(graph, {a1, b1, a2}) plan = executor.migration_plan({a1}) self.assertEqual(plan, [(a2_impl, True)]) def test_minimize_rollbacks_branchy(self): """ Minimize rollbacks when target has multiple in-app children. a: 1 <---- 3 <--\ \ \- 2 <--- 4 \ \ b: \- 1 <--- 2 """ a1_impl = FakeMigration('a1') a1 = ('a', '1') a2_impl = FakeMigration('a2') a2 = ('a', '2') a3_impl = FakeMigration('a3') a3 = ('a', '3') a4_impl = FakeMigration('a4') a4 = ('a', '4') b1_impl = FakeMigration('b1') b1 = ('b', '1') b2_impl = FakeMigration('b2') b2 = ('b', '2') graph = MigrationGraph() graph.add_node(a1, a1_impl) graph.add_node(a2, a2_impl) graph.add_node(a3, a3_impl) graph.add_node(a4, a4_impl) graph.add_node(b1, b1_impl) graph.add_node(b2, b2_impl) graph.add_dependency(None, a2, a1) graph.add_dependency(None, a3, a1) graph.add_dependency(None, a4, a2) graph.add_dependency(None, a4, a3) graph.add_dependency(None, b2, b1) graph.add_dependency(None, b1, a1) graph.add_dependency(None, b2, a2) executor = MigrationExecutor(None) executor.loader = FakeLoader(graph, {a1, b1, a2, b2, a3, a4}) plan = executor.migration_plan({a1}) should_be_rolled_back = [b2_impl, a4_impl, a2_impl, a3_impl] exp = [(m, True) for m in should_be_rolled_back] self.assertEqual(plan, exp) def test_backwards_nothing_to_do(self): """ If the current state satisfies the given target, do nothing. a: 1 <--- 2 b: \- 1 c: \- 1 If a1 is applied already and a2 is not, and we're asked to migrate to a1, don't apply or unapply b1 or c1, regardless of their current state. """ a1_impl = FakeMigration('a1') a1 = ('a', '1') a2_impl = FakeMigration('a2') a2 = ('a', '2') b1_impl = FakeMigration('b1') b1 = ('b', '1') c1_impl = FakeMigration('c1') c1 = ('c', '1') graph = MigrationGraph() graph.add_node(a1, a1_impl) graph.add_node(a2, a2_impl) graph.add_node(b1, b1_impl) graph.add_node(c1, c1_impl) graph.add_dependency(None, a2, a1) graph.add_dependency(None, b1, a1) graph.add_dependency(None, c1, a1) executor = MigrationExecutor(None) executor.loader = FakeLoader(graph, {a1, b1}) plan = executor.migration_plan({a1}) self.assertEqual(plan, [])