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Graph/async-callable-coroutine-mismatch

AntiPattern

Async Callable Returns Coroutine

async-callable-coroutine-mismatch

Async call sites mis-handle async callables—where a framework expects an object with enter/exit or a handler function, it receives an unawaited coroutine, causing missing lifecycle execution, stalled tests/requests, and broken mocks validation.

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Updated7/17/2026

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30 linked nodes

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Load the async user data with a Suspense-compatible async pattern (e.g., using `leo-query`’s `query`/`subscribe`) so the component waits until `currentUser` is available before rendering.

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Mock axios.get and await the assertion with waitFor()

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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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If you convert all operations to perform asynchronously (using `aiosqlite`) , the issue will be mitigated. — When a route in FastAPI is listed as asynchronous (`async def`). Tension: that doesn't fully solve the inherent single writer problem of Sqlite. Outcome: Here's a fully operational update of the FastAPI server logic:.

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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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I also offer an alternative `executor` class which can preserve the contextvar values across threads — when YOUR code is the one making the `loop.run_in_executor` call. Tension: in this example, the code making this is the framework code. Outcome: but that can only be used when YOUR code is the one making the `loop.run_in_executor` call.

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python interpreter just pauses one task and looks at other — In your scenerio where you use asynchronous. Tension: it is not completly usesless. Outcome: Think it like a round-robin.

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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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call_count is 0. Tension: This generates an error indicating that call_count is 0. Outcome: Check for `await_count` instead of `call_count`.

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Using `asyncio.sleep()` in a loop is perfectly fine. Tension: every time you `await` the sleep, you effectively yield control back to the event loop. Outcome: calling `asyncio.sleep(0)` does not sleep at all, but only yields control back to the event loop.

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I'd like to use `AsyncSession.sync_session` — async def get_session() -> AsyncSession: session = SessionLocal(). Tension: the code below fails with error. Outcome: use `AsyncSession.sync_session` but the code below fails with error.

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The correct code should look something like that — `run_in_executor` has this specification: `awaitable loop.run_in_executor(executor, func, *args)`. Tension: You passed `func` as first argument, but you need `executor` to come first, `func` should be second, and then `*args`. Outcome: with ThreadPoolExecutor() as pool: # or maybe ProcessPoolExecutor.

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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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implementing this retry behavior all over the place — axiosInstance.js. Tension: handle the retry logic. Outcome: you could try using a response interceptor to abstract and handle the retry logic.

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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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How can I get hold of the query metrics in this async setup? — The Couchbase documentation mentions to switch to the Reactive and Async APIs. Tension: the blocking API is really just a wrapper: it contains both the rows and the metadata (including metrics). In the reactive API this is split. Outcome: you can also call `result.metaData()` to access metrics, warnings, and the rest of the metadata.

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Use asynchronous sending with callbacks. — If you're using KafkaTemplate.send() without handling the ListenableFuture returned. Tension: you're effectively blocking the calling thread until the message is acknowledged by the Kafka broker. Outcome: The addCallback method allows you to execute code when the send operation succeeds or fails, without blocking the main thread.

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You can try `Mono.fromCallable()`. Tension: `Mono.just()` is not good for blocking operations. Outcome: `subscribeOn()` is when the execution starts in a separate thread pool that you define.

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You can use `async_compose` to create the composed operation — This initiation function can be used with any completion token. Tension: but I'd prefer a more lightweight approach. Outcome: Consider the `co_composed` initiator or `asio::deferred`.

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

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