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npx skills add https://github.com/secondsky/claude-skills --skill api-testingBefore you start
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API Testing
Expert knowledge for testing HTTP APIs with Supertest (TypeScript/JavaScript) and httpx/pytest (Python).
TypeScript/JavaScript (Supertest)
Installation
bash
# Using Bun
bun add -d supertest @types/supertest
# or: npm install -D supertest @types/supertestBasic Setup
typescript
import { describe, it, expect } from 'vitest'
import request from 'supertest'
import { app } from './app'
describe('API Tests', () => {
it('returns health status', async () => {
const response = await request(app)
.get('/api/health')
.expect(200)
expect(response.body).toEqual({ status: 'ok' })
})
it('creates a user', async () => {
const response = await request(app)
.post('/api/users')
.send({ name: 'John Doe', email: 'john@example.com' })
.expect(201)
expect(response.body).toMatchObject({
id: expect.any(Number),
name: 'John Doe',
})
})
it('validates required fields', async () => {
await request(app)
.post('/api/users')
.send({ name: 'John Doe' })
.expect(400)
})
})Request Methods
typescript
// GET
await request(app).get('/api/users').expect(200)
// POST with body
await request(app)
.post('/api/users')
.send({ name: 'John' })
.expect(201)
// PUT
await request(app)
.put('/api/users/1')
.send({ name: 'Jane' })
.expect(200)
// DELETE
await request(app).delete('/api/users/1').expect(204)Headers and Query Parameters
typescript
// Set headers
await request(app)
.get('/api/protected')
.set('Authorization', 'Bearer token123')
.expect(200)
// Query parameters
await request(app)
.get('/api/users')
.query({ page: 1, limit: 10 })
.expect(200)Authentication Testing
typescript
describe('Authentication', () => {
let authToken: string
beforeAll(async () => {
const response = await request(app)
.post('/api/auth/login')
.send({ email: 'user@example.com', password: 'password123' })
.expect(200)
authToken = response.body.token
})
it('accesses protected endpoint', async () => {
await request(app)
.get('/api/protected')
.set('Authorization', `Bearer ${authToken}`)
.expect(200)
})
it('rejects without token', async () => {
await request(app).get('/api/protected').expect(401)
})
})Error Handling
typescript
it('handles validation errors', async () => {
const response = await request(app)
.post('/api/users')
.send({ email: 'invalid-email' })
.expect(400)
expect(response.body).toMatchObject({
error: 'Validation failed',
details: expect.any(Array),
})
})
it('handles not found', async () => {
await request(app).get('/api/users/999999').expect(404)
})Python (httpx + pytest)
Installation
bash
uv add --dev httpx pytest-asyncioBasic Setup
python
import pytest
from fastapi.testclient import TestClient
from main import app
client = TestClient(app)
def test_health_check():
response = client.get("/api/health")
assert response.status_code == 200
assert response.json() == {"status": "ok"}
def test_create_user():
response = client.post(
"/api/users",
json={"name": "John Doe", "email": "john@example.com"}
)
assert response.status_code == 201
data = response.json()
assert data["name"] == "John Doe"
assert "id" in data
def test_not_found():
response = client.get("/api/users/999")
assert response.status_code == 404Fixtures
python
@pytest.fixture
def auth_token(client):
response = client.post(
"/api/auth/login",
json={"email": "user@example.com", "password": "password123"}
)
return response.json()["token"]
def test_protected_endpoint(client, auth_token):
response = client.get(
"/api/protected",
headers={"Authorization": f"Bearer {auth_token}"}
)
assert response.status_code == 200File Upload
python
def test_file_upload(client, tmp_path):
test_file = tmp_path / "test.txt"
test_file.write_text("test content")
with open(test_file, "rb") as f:
response = client.post(
"/api/upload",
files={"file": ("test.txt", f, "text/plain")}
)
assert response.status_code == 200GraphQL Testing
typescript
it('queries GraphQL endpoint', async () => {
const query = `
query GetUser($id: ID!) {
user(id: $id) { id name email }
}
`
const response = await request(app)
.post('/graphql')
.send({ query, variables: { id: '1' } })
.expect(200)
expect(response.body.data.user).toMatchObject({
id: '1',
name: expect.any(String),
})
})Performance Testing
typescript
it('responds within acceptable time', async () => {
const start = Date.now()
await request(app).get('/api/users').expect(200)
const duration = Date.now() - start
expect(duration).toBeLessThan(100) // 100ms threshold
})Best Practices
- Group related endpoints in
describeblocks - Reset database between tests
- Validate status codes first
- Check response structure
- Test error message format
- Mock external services
- Test both happy path and error cases
See Also
vitest-testing- Unit testing frameworkplaywright-testing- E2E API testingtest-quality-analysis- Test quality patterns
