TDD for FastAPI

Drive FastAPI API design with pytest-based test-driven development workflows.

Updated Apr 10, 2023

Search Tags:#testing #tdd #pytest #fastapi #async #mocking #httpx

Ready to run

npx skills add https://github.com/sajankp/to-do --skill tdd-for-fastapi

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: TDD for FastAPI
Source: https://github.com/sajankp/to-do/tree/main/.agent/skills/tdd-fastapi
Command: npx skills add https://github.com/sajankp/to-do --skill tdd-for-fastapi

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Enables teams to drive FastAPI development by writing tests before implementation, reducing ambiguity and guiding design decisions early.

Core Features & Use Cases

TDD Cycle: RED, GREEN, REFACTOR guidance to structure tests and minimal code efficiently.
Async Endpoint Testing: Patterns for testing FastAPI endpoints asynchronously using httpx and TestClient.
Mocks & Fixtures: Strategies for mocking MongoDB collections and providing fixtures for authenticated scenarios.
Endpoint Evolution: Worked examples showing how tests evolve alongside new routes and refactors.

Quick Start

Create a failing test first, run it to confirm failure, implement just enough code to pass, then refactor for readability.

Frequently Asked Questions about TDD for FastAPI

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I test FastAPI endpoints asynchronously with pytest?▼

Test FastAPI endpoints asynchronously using httpx and pytest TestClient to execute API routes. This approach creates deterministic, isolated tests by mocking MongoDB collections and providing fixtures for authenticated scenarios.

What is the best way to structure FastAPI test-driven development?▼

FastAPI test-driven development follows the RED, GREEN, REFACTOR cycle: write a failing test first, implement minimal code to pass, then refactor for readability. This reduces ambiguity and guides API design decisions early.

How do I mock MongoDB collections in FastAPI tests?▼

Mock MongoDB collections in FastAPI tests using mocking utilities to create deterministic, isolated tests. This strategy provides fixtures for authenticated scenarios without requiring a live database connection.

Do I need httpx to test asynchronous FastAPI endpoints?▼

Yes, httpx is required to test asynchronous FastAPI endpoints. It works alongside pytest and mocking utilities to create isolated tests with fixtures and asynchronous endpoint support.

Can I drive FastAPI authentication flow design with tests first?▼

Yes, drive FastAPI authentication flow design by writing tests before implementation. The approach covers authentication flows with mocked fixtures, reducing ambiguity and guiding security design decisions early.

Why does my FastAPI TDD cycle fail to isolate MongoDB dependencies?▼

FastAPI TDD cycles fail to isolate MongoDB dependencies without proper mocking utilities. Use fixtures and mocking strategies to create deterministic tests separate from database state.