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Graph/async-contract-and-lifecycle-mismatch

AntiPattern

Async Context Contract Breaks

async-contract-and-lifecycle-mismatch

Async mechanisms fail because a mock/handler/factory returns the wrong callable shape (coroutine vs async context manager), or because async lifecycle is reused across tests, causing incompatible event-loop state and follow-on routing/type errors.

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Updated7/6/2026

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30 linked nodes

MATCHESSolution

delete the async from `fake_execute` — your `AsyncContextMock` needs to handle both use cases in your endpoint `await conn.execute()` and `async with conn.execute()`. Outcome: just make it a regular function so it returns your context manager directly, no coroutine wrapper.

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for `cursor.fetchone.return_value`, just use (2,) directly — `cursor.fetchone.return_value`. Tension: AsyncMock already makes it awaitable. Outcome: wrapping it again messes things up.

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single worker running async loop. Outcome: So you have a single worker running async loop and you block that loop.

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Pass `BackgroundTasks` from the route into your dependency. — when declared inside an async dependency. Tension: the background job never runs. Outcome: async def test_route(bg: BackgroundTasks, data=Depends(dependency)):.

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Change the `mocked_app` and database `client` fixtures from `scope='session'` to `scope='function'` so each test gets a fresh app/client setup with a clean lifecycle.

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mock_client.update_one = AsyncMock(return_value=AsyncMock(matched_count=1, modified_count=1)). Outcome: Here the minimal code to make your example works.

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Removing `async` before the function definition solved it. — class LoggingAPIRoute(APIRoute):. Outcome: def get_route_handler(self) -> Callable:.

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Move the persistence/cleanup logic into code that runs at the end of the background task (or otherwise extend lifecycle explicitly for the background task), rather than relying on the request-scoped `asynccontextmanager` teardown for those updates.

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Use pytest_asyncio.fixture NOT pytest.fixture — @pytest_asyncio.fixture(scope='session', loop_scope='session'). Tension: async def my_fixture():. Outcome: yield 'foo'.

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You need to install helper packages, such as `anyio` or `pytest-asyncio`. — Async fixtures do not work out of the box. Tension: NB. Use pytest_asyncio.fixture NOT pytest.fixture. Outcome: Example.

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Change the engine async fixture from session scope to function scope (remove scope="session") so all async fixtures/tests run on the same event loop, preventing the cross-loop Future/Task error.

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using `magicmock` to mock it could lead to unusual or unexpected behavior when checking for call counts — Since `get_item` might be an asynchronous function in your middleware. Tension: using `magicmock` to mock it could lead to unusual or unexpected behavior. Outcome: which is designed to work with async functions.

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the reason for the various threads appearing in the logs — when you pass a synchronous generator to `EventSourceResponse`. Tension: a normal `def` function instead of `async def`. Outcome: please take a look at the implementation of the `EventSourceResponse` class.

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use `pytest_asyncio` and the async fixture — If you don't want to utilize an `AsyncClient` like the one by `httpx`. Tension: ensuring that the FastAPI app's lifespan context correctly works.

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any time you have an I/O bound process with lots of idle time — waiting for user input, waiting for a TLS handshake. Tension: wrapping it in an async task can let other code run.

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when I create the test client. Tension: The 'app' shortcut is now deprecated. Outcome: async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as async_test_client:.

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mock/fake/dummy S3 — simulate your desired test scenarios. Outcome: remove S3 from the problem and replace it with something that provides the same contract as S3.

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An async function was passed to useActionState.

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Or you can use `async/await` and `try/catch` — createAsyncThunk. Outcome: return data.

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Avoid running multiple DB operations concurrently on the same session by removing asyncio.gather and iterating sequentially, and/or use an async_scoped_session so each task uses its own session.

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Update the Context state from within the SignalR handler by invoking context methods (e.g., incorporating/using the patrols and update functions directly in the SignalR call path) so the global state is actually changed when messages arrive.

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case "CallbackRouteError": return { error: "Invalid credentials!" } — in my `login.ts` server action in the switch case clause. Tension: to return the correct errors. Outcome: bypass this error.

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Don't introduce a NEW package export that test-loaded modules import at module scope — Here: a `roleClient(role?)` helper in the consumer package (`etl/llm-route.ts`). Tension: it forces you to update every `vi.mock` factory, and missing one re-breaks CI.

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Alternately, you could treat tests with mocks as unit tests which don't involve JavaFX code.

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I think it is better to use a custom context manager — if you need to isolate test methods from each other. Tension: you need to isolate test methods from each other. Outcome: here is what I am using.

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Rewrite the test as an async test and run it with an async test runner (e.g., pytest.mark.asyncio), using await on the async ORM methods (acreate/acount) instead of asyncio.run().

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Use Component.Task (TaskSource) for all async work inside components — inside components. Tension: it auto-cancels when the component is destroyed.

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Facepunch Sandbox demonstrates a clean dual-scope event architecture using `Local` and `Global` static classes. Tension: Difficulty implementing cancellable events.

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Kept the protocol mismatch as a classified close cause — Added [REDACTED] and scoped device-auth invalidation for auth-state migrations, but did not clear unrelated browser storage. Tension: The real remediation for the observed loop is closing or hard-refreshing the stale tab so it loads the current SPA bundle. Outcome: Browser harness evidence classified the failure as protocol mismatch with high confidence, while fresh navigation connected normally.

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Rebuilt App.tsx as the OracleController beat machine. Outcome: running the authored cascade arrest→anchor→recognition→locked on setTimeout timers.

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