automating-api-testing

name	automating-api-testing
description	Test automate API endpoint testing including request generation, validation, and comprehensive test coverage for REST and GraphQL APIs. Use when testing API contracts, validating OpenAPI specifications, or ensuring endpoint reliability. Trigger with phrases like "test the API", "generate API tests", or "validate API contracts".
allowed-tools	Read, Write, Edit, Grep, Glob, Bash(test:api-*)
version	1.27.0
author	Jeremy Longshore <[e-mail]>
license	MIT
tags	["testing","api","graphql"]
compatibility	Designed for Claude Code

API Test Automation

Overview

Automate comprehensive API endpoint testing for REST and GraphQL APIs including request generation, response validation, schema compliance, authentication flows, and error handling. Supports Supertest (Node.js), REST-assured (Java), httpx/pytest (Python), Postman/Newman collections, and Pact for consumer-driven contract testing.

Prerequisites

• API testing library installed (Supertest, REST-assured, httpx, or Postman/Newman)
• API specification file (OpenAPI/Swagger YAML/JSON or GraphQL SDL)
• Target API running in a test environment with seeded data
• Authentication credentials or API keys for protected endpoints
• JSON Schema validator (Ajv, jsonschema, or built-in framework assertions)

Instructions

1. Read the API specification and extract all endpoints:
   • Parse OpenAPI spec to catalog every path, HTTP method, request schema, and response schema.
   • For GraphQL APIs, introspect the schema to list queries, mutations, and subscriptions.
   • Document authentication requirements per endpoint (API key, Bearer token, OAuth, none).
2. Generate test cases for each endpoint:
   • Success cases: Send valid requests matching the schema and assert 200/201 responses.
   • Validation errors: Send requests with missing required fields, wrong types, and out-of-range values; assert 400 responses.
   • Authentication: Test with valid, expired, and missing credentials; assert 200, 401, and 403 respectively.
   • Not found: Request non-existent resources; assert 404 responses.
   • Idempotency: Send the same PUT/DELETE request twice and verify consistent behavior.
3. Validate response structure against schemas:
   • Assert response Content-Type matches expected (application/json, etc.).
   • Validate response body against the OpenAPI response schema using JSON Schema validation.
   • Check response headers (Cache-Control, Rate-Limit headers, CORS headers).
   • Verify pagination metadata (total count, page number, next/previous links).
4. Test CRUD lifecycle for resource endpoints:
   • Create a resource (POST) and capture the ID.
   • Read it back (GET) and verify all fields match.
   • Update it (PUT/PATCH) and verify changes persisted.
   • Delete it (DELETE) and verify subsequent GET returns 404.
5. Test error handling and edge cases:
   • Send excessively large payloads and verify 413 or graceful rejection.