Add tests for the migrate command and fix a bug they exposed

tests/migrations/test_commands.py

@@ -0,0 +1,37 @@
+from django.core.management import call_command
+from django.test.utils import override_settings
+from .test_base import MigrationTestBase
+
+
+class CommandTests(MigrationTestBase):
+    """
+    Tests running the commands (migrate, makemigrations).
+    """
+
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
+    def test_migrate(self):
+        """
+        Tests basic usage of the migrate command.
+        """
+        # Make sure no tables are created
+        self.assertTableNotExists("migrations_author")
+        self.assertTableNotExists("migrations_tribble")
+        self.assertTableNotExists("migrations_book")
+        # Run the migrations to 0001 only
+        call_command("migrate", "migrations", "0001", verbosity=0)
+        # Make sure the right tables exist
+        self.assertTableExists("migrations_author")
+        self.assertTableExists("migrations_tribble")
+        self.assertTableNotExists("migrations_book")
+        # Run migrations all the way
+        call_command("migrate", verbosity=0)
+        # Make sure the right tables exist
+        self.assertTableExists("migrations_author")
+        self.assertTableNotExists("migrations_tribble")
+        self.assertTableExists("migrations_book")
+        # Unmigrate everything
+        call_command("migrate", "migrations", "zero", verbosity=0)
+        # Make sure it's all gone
+        self.assertTableNotExists("migrations_author")
+        self.assertTableNotExists("migrations_tribble")
+        self.assertTableNotExists("migrations_book")