api-testing

Import supertest and pass your Express app to request(app), then chain methods like .get(), .post(), .send(), and .expect() to assert status codes. Use expect() on response.body to validate the returned JSON structure.

Use FastAPI's TestClient to create a client from your app, then call client.get() or client.post() with JSON payloads. Assert on response.status_code and response.json() to verify behavior, and use pytest fixtures for shared setup like auth tokens.

Supertest is the standard choice for TypeScript/JavaScript apps like Express, while httpx with pytest or FastAPI's TestClient is the Python equivalent. Both support in-process testing without running a live server.

Log in via a POST to your auth endpoint in a beforeAll hook or pytest fixture, extract the token from the response, then pass it as an Authorization Bearer header on subsequent requests. Also test that requests without a token return 401.

Yes, send a POST request to your GraphQL endpoint with the query string and variables in the request body. Assert on response.body.data to verify the returned fields match expected values.

Tests often fail due to shared database state leaking between test cases. Reset the database between tests, group related endpoints in describe blocks, and mock external services to keep tests deterministic.