Refactor code structure for improved readability and maintainability

tests/unit/test_lifecycle.py

@@ -0,0 +1,89 @@
+import asyncio
+from typing import Any
+from unittest.mock import AsyncMock
+
+import pytest
+from fastapi import FastAPI
+
+from app import main
+from app.config import Settings
+
+
+class FakeBroker:
+    instance: "FakeBroker"
+
+    def __init__(self, *_: Any, **__: Any) -> None:
+        type(self).instance = self
+        self.started = False
+        self.stopped = False
+
+    async def start(self) -> None:
+        self.started = True
+
+    async def stop(self) -> None:
+        self.stopped = True
+
+
+class CooperativePublisher:
+    instance: "CooperativePublisher"
+
+    def __init__(self, *_: Any, **__: Any) -> None:
+        type(self).instance = self
+        self.stopped = False
+
+    async def run(self, stop_event: asyncio.Event) -> None:
+        await stop_event.wait()
+        self.stopped = True
+
+
+class StuckPublisher:
+    instance: "StuckPublisher"
+
+    def __init__(self, *_: Any, **__: Any) -> None:
+        type(self).instance = self
+        self.cancelled = False
+
+    async def run(self, _: asyncio.Event) -> None:
+        try:
+            await asyncio.Event().wait()
+        finally:
+            self.cancelled = True
+
+
+async def test_lifespan_starts_and_stops_resources(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    declare_topology = AsyncMock()
+    close_database = AsyncMock()
+    monkeypatch.setattr(main, "RabbitBroker", FakeBroker)
+    monkeypatch.setattr(main, "OutboxPublisher", CooperativePublisher)
+    monkeypatch.setattr(main, "declare_topology", declare_topology)
+    monkeypatch.setattr(main, "close_database", close_database)
+
+    async with main.lifespan(FastAPI()):
+        assert FakeBroker.instance.started is True
+
+    assert CooperativePublisher.instance.stopped is True
+    assert FakeBroker.instance.stopped is True
+    declare_topology.assert_awaited_once_with(FakeBroker.instance)
+    close_database.assert_awaited_once_with()
+
+
+async def test_lifespan_cancels_stuck_publisher(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setattr(main, "RabbitBroker", FakeBroker)
+    monkeypatch.setattr(main, "OutboxPublisher", StuckPublisher)
+    monkeypatch.setattr(main, "declare_topology", AsyncMock())
+    monkeypatch.setattr(main, "close_database", AsyncMock())
+    monkeypatch.setattr(
+        main,
+        "settings",
+        Settings(outbox_publish_timeout=0.001, outbox_poll_interval=0.001),
+    )
+
+    async with main.lifespan(FastAPI()):
+        pass
+
+    assert StuckPublisher.instance.cancelled is True
+    assert FakeBroker.instance.stopped is True