Refs #31117 -- Made various tests properly handle unexpected databases aliases.

- Used selected "databases" instead of django.db.connections.
- Made routers in tests.migrations skip migrations on unexpected
  databases.
- Added DiscoverRunnerGetDatabasesTests.assertSkippedDatabases() hook
  which properly asserts messages about skipped databases.

3 files changed, 11 insertions, 8 deletions

diff --git a/tests/migrations/routers.py b/tests/migrations/routers.py
index 21dfc561bd..bc036382a7 100644
--- a/tests/migrations/routers.py
+++ b/tests/migrations/routers.py
@@ -1,5 +1,6 @@
-class EmptyRouter:
-    pass
+class DefaultOtherRouter:
+    def allow_migrate(self, db, app_label, model_name=None, **hints):
+        return db in {'default', 'other'}
 
 
 class TestRouter:
@@ -9,5 +10,5 @@ class TestRouter:
         """
         if model_name == 'tribble':
             return db == 'other'
-        elif db == 'other':
+        elif db != 'default':
             return False
diff --git a/tests/migrations/test_base.py b/tests/migrations/test_base.py
index 45c5472b0f..c4c8b1ee6c 100644
--- a/tests/migrations/test_base.py
+++ b/tests/migrations/test_base.py
@@ -24,7 +24,7 @@ class MigrationTestBase(TransactionTestCase):
 
     def tearDown(self):
         # Reset applied-migrations state.
-        for db in connections:
+        for db in self.databases:
             recorder = MigrationRecorder(connections[db])
             recorder.migration_qs.filter(app='migrations').delete()
 
diff --git a/tests/migrations/test_commands.py b/tests/migrations/test_commands.py
index 5f57dc7cad..b98b77cd99 100644
--- a/tests/migrations/test_commands.py
+++ b/tests/migrations/test_commands.py
@@ -129,7 +129,7 @@ class MigrateTests(MigrationTestBase):
         that check.
         """
         # Make sure no tables are created
-        for db in connections:
+        for db in self.databases:
             self.assertTableNotExists("migrations_author", using=db)
             self.assertTableNotExists("migrations_tribble", using=db)
         # Run the migrations to 0001 only
@@ -192,7 +192,7 @@ class MigrateTests(MigrationTestBase):
         call_command("migrate", "migrations", "zero", verbosity=0)
         call_command("migrate", "migrations", "zero", verbosity=0, database="other")
         # Make sure it's all gone
-        for db in connections:
+        for db in self.databases:
             self.assertTableNotExists("migrations_author", using=db)
             self.assertTableNotExists("migrations_tribble", using=db)
             self.assertTableNotExists("migrations_book", using=db)
@@ -931,7 +931,7 @@ class MakeMigrationsTests(MigrationTestBase):
 
                 # With a router that doesn't prohibit migrating 'other',
                 # consistency is checked.
-                with self.settings(DATABASE_ROUTERS=['migrations.routers.EmptyRouter']):
+                with self.settings(DATABASE_ROUTERS=['migrations.routers.DefaultOtherRouter']):
                     with self.assertRaisesMessage(Exception, 'Other connection'):
                         call_command('makemigrations', 'migrations', verbosity=0)
                 self.assertEqual(has_table.call_count, 4)  # 'default' and 'other'
@@ -944,12 +944,14 @@ class MakeMigrationsTests(MigrationTestBase):
                 allow_migrate.assert_any_call('other', 'migrations', model_name='UnicodeModel')
                 # allow_migrate() is called with the correct arguments.
                 self.assertGreater(len(allow_migrate.mock_calls), 0)
+                called_aliases = set()
                 for mock_call in allow_migrate.mock_calls:
                     _, call_args, call_kwargs = mock_call
                     connection_alias, app_name = call_args
-                    self.assertIn(connection_alias, ['default', 'other'])
+                    called_aliases.add(connection_alias)
                     # Raises an error if invalid app_name/model_name occurs.
                     apps.get_app_config(app_name).get_model(call_kwargs['model_name'])
+                self.assertEqual(called_aliases, set(connections))
                 self.assertEqual(has_table.call_count, 4)
 
     def test_failing_migration(self):