Can I test asynchronous FastAPI endpoints?

Absolutely. The skill defaults to using pytest-anyio and httpx.AsyncClient with ASGITransport for modern, non-blocking API tests.

What is the preferred testing methodology?

The skill promotes the Arrange-Act-Assert (AAA) pattern and emphasizes testing public interfaces (HTTP contracts for backends, DOM accessibility for frontends) over implementation details.

Does this skill support Svelte 5 runes?

Yes, it includes specific patterns for testing Svelte 5 components and handles runes like $state and $derived using Vitest and .svelte.test.ts extensions.

How does it handle external API calls in frontend tests?

It recommends and provides configuration patterns for Mock Service Worker (MSW) to intercept and mock network requests at the fetch layer, ensuring tests remain isolated.

FastAPI & Svelte Testing Specialist

Name: FastAPI & Svelte Testing Specialist
Author: AnExiledDev

byAnExiledDev

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Security & Testing

Implements robust testing patterns for FastAPI backend endpoints and Svelte 5 frontend components using pytest and Vitest.

This skill provides specialized guidance for writing high-quality tests in modern web stacks, specifically focusing on FastAPI and Svelte 5. It streamlines the creation of async API tests using httpx and pytest-anyio, while offering expert patterns for Svelte component testing with Vitest and MSW. Whether you need to mock complex dependencies, test Server-Sent Events (SSE), or simulate user interactions in a reactive UI, this skill ensures your test suite follows industry best practices like the Arrange-Act-Assert pattern and focuses on public interface behavior.

Key Features

01Network-level intercepting and fetch mocking with Mock Service Worker (MSW)

02Specialized testing for Server-Sent Events (SSE) and streaming endpoints

036 GitHub stars

04Svelte 5 component testing with Vitest and @testing-library/svelte

05Dependency injection and mocking strategies for Python backends

06Async testing patterns for FastAPI using httpx and ASGITransport

Use Cases

01Setting up a comprehensive test suite for a new SvelteKit project using Vitest

02Verifying complex UI behavior and async state updates in Svelte 5 components

03Mocking database dependencies and authenticated users in FastAPI endpoints

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add anexileddev/codeforge testing

For use in Claude.ai and ChatGPT

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