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Graph/async-test-harness-drift

AntiPattern

Async Test Harness Drift

async-test-harness-drift

Async test setup and mocks drift out of alignment—async fixtures, client lifecycle, and awaited calls mismatch—so event loops block or coroutines are treated as context managers, leaving stale connections and flaky behavior across tests.

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Updated8/4/2026

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30 linked nodes

MATCHESSolution

Instead of mocking local storage, I just need to access it directly — This is my test code using Jest + TypeScript. Tension: mocking local storage. Outcome: The final test should look like this:.

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handle a scenario when the code is fine but backend went offline — prefetching data with usePrefetchQuery. Tension: prefetch works.

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

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Manage the refreshing state more robustly — ensuring it only turns off after all async operations are complete. Tension: remove the arbitrary timeout. Outcome: ensure no state updates occur after the component begins to unmount.

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beforeEach(() => { vi.useRealTimers() }) — to the describe of the tests. Tension: I cannot modify and remove the setup scripts. Outcome: afterEach(() => { vi.useFakeTimers() }).

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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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The following test case is now passing. — mock-test.

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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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Using a `session-scoped` pytest fixture, for managing the event loop — which ensures the same event loop will be used. Outcome: loop.close().

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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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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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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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Initialize Eureka using the async API (e.g., `eureka_client.init_async(...)`) and/or move initialization into an appropriate async startup hook so it doesn’t start a new event loop at import time.

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Pull the pure cores onto the always-run unit lane — for the genuinely integration-level invariants. Tension: a skipped test is not a passing test.

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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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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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@ExtendWith({ MockitoExtension.class, ApplicationExtension.class }) — To use TestFX to test a JavaFX application. Tension: how do you do both at the same time? Outcome: it works for this case.

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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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template test. Outcome: the assertion was narrowed.

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Added focused tests for snapshot fallback, cleanup return values, extraction drain early exit, parallel parsing, and concurrency limits — the benchmark TypeScript typecheck from its package, the orchestrator --help command, and the full repository Vitest suite. Tension: the graph integration functions were stubbed. Outcome: Ran the focused Vitest tests, the benchmark TypeScript typecheck from its package, the orchestrator --help command, and the full repository Vitest suite successfully.

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Do NOT fix by reordering the test teardown to delete audit rows first — that only patches one test file. Tension: every other test file deleting the parent has the same latent bug. Outcome: Fix the schema once.

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Defer ALL database imports into the script's `main()` function. — Test file imports only the pure helpers — no DATABASE_URL needed, no mocks. Tension: dynamic `await import()` is slightly slower on first DB call. Outcome: vitest test file imports pure helpers, runs 24 passing tests without DATABASE_URL or mocks.

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