pytest

Fix a Django N+1 query and protect it with a query-count test

Repairs a Django serialization path with select_related and prefetch_related, then locks the query shape with a regression test.

How do pytest fixture dependencies and scopes work, and how do you choose a scope?

Explains pytest fixture dependency resolution, caching, lifetime, and the isolation cost of wider scopes.

How do yield fixtures and safe teardown work in pytest?

Explains reverse-order fixture cleanup and designs teardown that remains safe when setup or tests fail.

How do you test Django transaction.on_commit behavior?

Verifies commit callbacks without confusing callback registration with durable external delivery.

How do you use FastAPI dependency overrides without leaking test state?

Overrides FastAPI boundaries for focused tests and restores the global override mapping reliably.

How do you use pytest parametrization without making tests unreadable?

Uses parametrization for one behavior across meaningful cases while keeping failures and intent easy to read.

Python Backend

Python backend interview preparation grounded in real service development.

A backend-focused Python preparation path covering language semantics, typing, FastAPI, Django, concurrency, data access, testing, security, background work, reliability, and production diagnosis.