Drills

Build a validated FastAPI create endpoint with safe models

Builds a FastAPI POST boundary with separate input/output models, forbidden extra fields, domain mapping, and a 201 response.

FastAPIPydanticPython

Fetch URLs concurrently with a bound, timeout, and structured cleanup

Implements bounded asyncio HTTP concurrency with one client, per-call deadlines, TaskGroup ownership, and deterministic cleanup.

Python

Practice drill

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.

DjangopytestPython

Handle an optimistic version conflict with SQLAlchemy

Uses SQLAlchemy version counters and an HTTP precondition to reject stale writes without silently overwriting newer state.

FastAPIPythonSQLAlchemy

Implement an idempotent retryable Celery provider task

Builds a Celery task that survives timeout ambiguity, retries temporary failures, and records one durable business outcome.

Python

Implement an immutable USD money value object in Python

Builds a frozen dataclass around Decimal with explicit scale, validation, arithmetic, ordering, and value equality.

Python

Implement a persisted idempotent FastAPI POST

Implements a database-backed idempotency boundary that replays one response and rejects key reuse with a different request.

FastAPIPythonSQLAlchemy

Implement stable keyset pagination with async SQLAlchemy

Builds descending keyset pagination with a unique tie-breaker, opaque cursor, limit-plus-one query, and stable next page.

PythonSQLAlchemy

Reserve Django inventory safely under concurrent requests

Uses a database transaction and row lock to keep stock non-negative when reservations race.

DjangoPython

Save an order and outbox event in one SQLAlchemy transaction

Persists business state and durable publication intent atomically while leaving broker delivery to an idempotent publisher.

PythonSQLAlchemy

Test a FastAPI resource-ownership boundary

Tests missing, unauthenticated, owner, and cross-owner access through FastAPI's real dependency and routing boundary.

FastAPIpytestPython

AlembicpytestPythonSQLAlchemy

Verify a PostgreSQL constraint with pytest and Testcontainers

Runs a migration-backed pytest integration test against PostgreSQL and proves case-insensitive email uniqueness.