feat: initialize governed postbox module

tests/test_migration.py

@@ -0,0 +1,61 @@
+from __future__ import annotations
+
+import importlib
+import unittest
+
+from alembic.migration import MigrationContext
+from alembic.operations import Operations
+from sqlalchemy import create_engine, inspect
+
+
+class PostboxMigrationTests(unittest.TestCase):
+    def test_baseline_creates_and_drops_owned_tables(self) -> None:
+        migration = importlib.import_module(
+            "govoplan_postbox.backend.migrations.versions."
+            "c7d2e5f8a1b4_v010_postbox_baseline"
+        )
+        engine = create_engine("sqlite:///:memory:")
+        try:
+            with engine.begin() as connection:
+                operations = Operations(MigrationContext.configure(connection))
+                original = migration.op
+                migration.op = operations
+                try:
+                    migration.upgrade()
+                    tables = set(inspect(connection).get_table_names())
+                    self.assertIn("postboxes", tables)
+                    self.assertIn("postbox_messages", tables)
+                    self.assertIn("postbox_deliveries", tables)
+                    self.assertIn("postbox_access_events", tables)
+                    message_columns = {
+                        column["name"]
+                        for column in inspect(connection).get_columns(
+                            "postbox_messages"
+                        )
+                    }
+                    self.assertTrue(
+                        {
+                            "ciphertext_ref",
+                            "signed_manifest_ref",
+                            "wrapped_keys",
+                            "key_epoch",
+                            "expires_at",
+                            "withdrawn_at",
+                        }.issubset(message_columns)
+                    )
+                    migration.downgrade()
+                    self.assertFalse(
+                        {
+                            table
+                            for table in inspect(connection).get_table_names()
+                            if table.startswith("postbox")
+                        }
+                    )
+                finally:
+                    migration.op = original
+        finally:
+            engine.dispose()
+
+
+if __name__ == "__main__":
+    unittest.main()