functional test for migrations on sqlite

* We commonly subvert running migrations in test land. Test land uses
  sqlite. By not constantly exercising this code path it atrophies. The
  smoke test here is to continuously exercise that code path.
* Add ci test to run migration tests separately, they take =~ 2-3
  minutes each on my laptop.
* The smoke tests also serves as an example of how to write migration
  tests.

.github/workflows/ci.yml

@@ -20,6 +20,10 @@ jobs:
         tests:
           - name: api-test
             command: /start_tests.sh
+          - name: api-test-migrations
+            command: /start_tests.sh
+            env:
+              PYTEST_ARGS: -n auto --migrations -m migration_test
           - name: api-lint
             command: /var/lib/awx/venv/awx/bin/tox -e linters
           - name: api-swagger
@@ -43,7 +47,10 @@ jobs:
           github-token: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Run check ${{ matrix.tests.name }}
-        run: AWX_DOCKER_CMD='${{ matrix.tests.command }}' make docker-runner
+        run: make docker-runner
+        env:
+          AWX_DOCKER_CMD: ${{ matrix.tests.command }}
+          PYTEST_ARGS: ${{ matrix.tests.env.PYTEST_ARGS }}
 
   dev-env:
     runs-on: ubuntu-latest

awx/main/migrations/_sqlite_helper.py

@@ -1,5 +1,3 @@
-import sys
-
 from django.db import migrations
 
 

awx/main/tests/functional/test_migrations.py

@@ -0,0 +1,44 @@
+import pytest
+
+from django_test_migrations.plan import all_migrations, nodes_to_tuples
+
+"""
+Most tests that live in here can probably be deleted at some point. They are mainly
+for a developer. When AWX versions that users upgrade from falls out of support that
+is when migration tests can be deleted. This is also a good time to squash. Squashing
+will likely mess with the tests that live here.
+
+The smoke test should be kept in here. The smoke test ensures that our migrations
+continue to work when sqlite is the backing database (vs. the default DB of postgres).
+"""
+
+
+@pytest.mark.django_db
+class TestMigrationSmoke:
+    def test_happy_path(self, migrator):
+        """
+        This smoke test runs all the migrations.
+
+        Example of how to use django-test-migration to invoke particular migration(s)
+        while weaving in object creation and assertions.
+
+        Note that this is more than just an example. It is a smoke test because it runs ALL
+        the migrations. Our "normal" unit tests subvert the migrations running because it is slow.
+        """
+        migration_nodes = all_migrations('default')
+        migration_tuples = nodes_to_tuples(migration_nodes)
+        final_migration = migration_tuples[-1]
+
+        migrator.apply_initial_migration(('main', None))
+        # I just picked a newish migration at the time of writing this.
+        # If someone from the future finds themselves here because the are squashing migrations
+        # it is fine to change the 0180_... below to some other newish migration
+        intermediate_state = migrator.apply_tested_migration(('main', '0180_add_hostmetric_fields'))
+
+        Instance = intermediate_state.apps.get_model('main', 'Instance')
+        # Create any old object in the database
+        Instance.objects.create(hostname='foobar', node_type='control')
+
+        final_state = migrator.apply_tested_migration(final_migration)
+        Instance = final_state.apps.get_model('main', 'Instance')
+        assert Instance.objects.filter(hostname='foobar').count() == 1

requirements/requirements_dev.txt

@@ -1,6 +1,7 @@
 build
 coreapi
 django-debug-toolbar==3.2.4
+django-test-migrations
 drf-yasg
 # pprofile - re-add once https://github.com/vpelletier/pprofile/issues/41 is addressed
 ipython>=7.31.1 # https://github.com/ansible/awx/security/dependabot/30