api-test-suite-builder

name api-test-suite-builder description Use when the user asks to generate API tests, create integration test suites, test REST endpoints, or build contract tests. API Test Suite Builder Tier: POWERFUL Category: Engineering Domain: Testing / API Quality Overview Scans API route definitions across frameworks (Next.js App Router, Express, FastAPI, Django REST) and auto-generates comprehensive test suites covering auth, input validation, error codes, pagination, file uploads, and rate limiting. Outputs ready-to-run test files for Vitest+Supertest (Node) or Pytest+httpx (Python). Core Capabilities Route detection — scan source files to extract all API endpoints Auth coverage — valid/invalid/expired tokens, missing auth header Input validation — missing fields, wrong types, boundary values, injection attempts Error code matrix — 400/401/403/404/422/500 for each route Pagination — first/last/empty/oversized pages File uploads — valid, oversized, wrong MIME type, empty Rate limiting — burst detection, per-user vs global limits When to Use New API added — generate test scaffold before writing implementation (TDD) Legacy API with no tests — scan and generate baseline coverage API contract review — verify existing tests match current route definitions Pre-release regression check — ensure all routes have at least smoke tests Security audit prep — generate adversarial input tests Route Detection Next.js App Router # Find all route handlers find ./app/api -name "route.ts" -o -name "route.js" | sort # Extract HTTP methods from each route file grep -rn "export async function\|export function" app/api/**/route.ts | \ grep -oE "(GET|POST|PUT|PATCH|DELETE|HEAD|OPTIONS)" | sort -u # Full route map find ./app/api -name "route.ts" | while read f; do route=$( echo $f | sed 's|./app||' | sed 's|/route.ts||' ) methods=$(grep -oE "export (async )?function (GET|POST|PUT|PATCH|DELETE)" " $f " | \ grep -oE "(GET|POST|PUT|PATCH|DELETE)" ) echo " $methods $route " done Express # Find all router files find ./src -name "*.ts" -o -name "*.js" | xargs grep -l "router\.\(get\|post\|put\|delete\|patch\)" 2>/dev/null # Extract routes with line numbers grep -rn "router\.\(get\|post\|put\|delete\|patch\)\|app\.\(get\|post\|put\|delete\|patch\)" \ src/ --include= "*.ts" | grep -oE "(get|post|put|delete|patch)\(['\"][^'\"]*['\"]" # Generate route map grep -rn "router\.\|app\." src/ --include= "*.ts" | \ grep -oE "\.(get|post|put|delete|patch)\(['\"][^'\"]+['\"]" | \ sed "s/\.\(.*\)('\(.*\)'/\U\1 \2/" FastAPI # Find all route decorators grep -rn "@app\.\|@router\." . --include= "*.py" | \ grep -E "@(app|router)\.(get|post|put|delete|patch)" # Extract with path and function name grep -rn "@\(app\|router\)\.\(get\|post\|put\|delete\|patch\)" . --include= "*.py" | \ grep -oE "@(app|router)\.(get|post|put|delete|patch)\(['\"][^'\"]*['\"]" Django REST Framework # urlpatterns extraction grep -rn "path\|re_path\|url(" . --include= "*.py" | grep "urlpatterns" -A 50 | \ grep -E "path\(['\"]" | grep -oE "['\"][^'\"]+['\"]" | head -40 # ViewSet router registration grep -rn "router\.register\|DefaultRouter\|SimpleRouter" . --include= "*.py" Test Generation Patterns Auth Test Matrix For every authenticated endpoint, generate: Test Case Expected Status No Authorization header 401 Invalid token format 401 Valid token, wrong user role 403 Expired JWT token 401 Valid token, correct role 2xx Token from deleted user 401 Input Validation Matrix For every POST/PUT/PATCH endpoint with a request body: Test Case Expected Status Empty body {} 400 or 422 Missing required fields (one at a time) 400 or 422 Wrong type (string where int expected) 400 or 422 Boundary: value at min-1 400 or 422 Boundary: value at min 2xx Boundary: value at max 2xx Boundary: value at max+1 400 or 422 SQL injection in string field 400 or 200 (sanitized) XSS payload in string field 400 or 200 (sanitized) Null values for required fields 400 or 422 Example Test Files → See references/example-test-files.md for details Generating Tests from Route Scan When given a codebase, follow this process: Scan routes using the detection commands above Read each route handler to understand: Expected request body schema Auth requirements (middleware, decorators) Return types and status codes Business rules (ownership, role checks) Generate test file per route group using the patterns above Name tests descriptively : "returns 401 when token is expired" not "auth test 3" Use factories/fixtures for test data — never hardcode IDs Assert response shape , not just status code Common Pitfalls Testing only happy paths — 80% of bugs live in error paths; test those first Hardcoded test data IDs — use factories/fixtures; IDs change between environments Shared state between tests — always clean up in afterEach/afterAll Testing implementation, not behavior — test what the API returns, not how it does it Missing boundary tests — off-by-one errors are extremely common in pagination and limits Not testing token expiry — expired tokens behave differently from invalid ones Ignoring Content-Type — test that API rejects wrong content types (xml when json expected) Best Practices One describe block per endpoint — keeps failures isolated and readable Seed minimal data — don't load the entire DB; create only what the test needs Use beforeAll for shared setup, afterAll for cleanup — not beforeEach for expensive ops Assert specific error messages/fields, not just status codes Test that sensitive fields (password, secret) are never in responses For auth tests, always test the "missing header" case separately from "invalid token" Add rate limit tests last — they can interfere with other test suites if run in parallel