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api-test-suite-builder

Testing & Quality
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Generate API test suites from route definitions across frameworks: auth, input validation, contract, k6 load testing, mocking, and OpenAPI-driven generation. Use when adding new APIs, auditing test coverage, or building regression suites.

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How to use this skill

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Source SKILL.md: https://github.com/borghei/Claude-Skills/blob/HEAD/engineering/api-test-suite-builder/SKILL.md

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API Test Suite Builder

Scan API route definitions across frameworks (Next.js App Router, Express, FastAPI, Django REST, Go net/http), analyze request/response schemas, and generate comprehensive test suites covering authentication, authorization, input validation, error handling, pagination, file uploads, rate limiting, contract testing, and load testing. Outputs ready-to-run test files for Vitest+Supertest (Node), Pytest+httpx (Python), or k6 (load testing).

Core Capabilities

  • Route detection & analysis — scan source files to extract endpoints, parse request/response schemas, detect auth middleware and authorization rules across Node, Python, and Go frameworks.
  • Test matrix generation — auth (valid/invalid/expired tokens, wrong roles), input validation (missing/wrong-type/boundary/injection), error paths (400/401/403/404/409/422/429/500), pagination, file uploads, and rate limiting.
  • Contract testing — OpenAPI-to-test generation, Pact consumer-driven contracts, schema snapshot testing for breaking-change detection.
  • Load testing — k6 scripts with ramp-up patterns and SLA thresholds, latency percentile tracking (P50/P95/P99), concurrent user simulation.

When to Use

  • New API added — generate a test scaffold before implementation (TDD).
  • Legacy API with no tests — scan and generate baseline coverage.
  • Pre-release — ensure all routes have at least smoke tests.
  • API contract change — detect and test breaking changes.
  • Security audit — generate adversarial input tests.
  • Performance validation — create load-test baselines.

Clarify First

Before generating the suite, confirm these inputs. If any is unknown or vague, ASK — do not assume:

  • Target framework — Vitest+Supertest, Pytest+httpx, or k6 (determines the emitted test-file format via --framework)
  • Spec or routes source — an OpenAPI spec or the source files to scan (the input the generator parses)
  • Test scope — auth, input validation, contract, load, or the full matrix (which test categories get generated)

Stop rule: ask only the 2-3 that most change the output. If the user says "just draft it," proceed and list your assumptions at the top of the artifact.

Tools

ToolPurposeCommand
test_generator.pyGenerate API test skeletons from an OpenAPI/Swagger specpython scripts/test_generator.py spec.json --framework vitest --output tests/
coverage_analyzer.pyCompare spec endpoints vs existing test files to find gapspython scripts/coverage_analyzer.py spec.json tests/ --threshold 95
contract_validator.pyValidate response samples against OpenAPI schema contractspython scripts/contract_validator.py spec.json samples/ --strict

References

Load the reference that matches the task — keep this file lean and pull detail on demand:

  • references/route-detection-and-matrices.md — per-framework route-detection shell commands and the full auth / input-validation / pagination test matrices with worked TypeScript examples. Read when scanning a codebase or writing the core test cases.
  • references/contract-and-load-testing.md — complete Pact consumer-driven contract test and k6 load-test scripts, plus the commands to run load tests locally, against staging, and in the cloud. Read when adding contract or performance tests.
  • references/workflow-and-quality.md — the 9-step generation workflow, reusable test-helper patterns (auth, authed request, factories), common pitfalls, best practices, a troubleshooting table, and the success-criteria bar. Read before generating a suite and before shipping it.

Scope & Limitations

This skill covers:

  • Generating test suites from route definitions for REST APIs across Node.js, Python, and Go frameworks
  • Authentication, authorization, input validation, pagination, and error-path test generation
  • Consumer-driven contract testing with Pact and schema snapshot validation
  • Load and performance testing script generation with k6 and Artillery

This skill does NOT cover:

  • GraphQL API testing (see engineering/api-design-reviewer for schema review patterns)
  • End-to-end browser testing or UI interaction testing (see engineering/playwright-pro)
  • Database migration testing or schema validation (see engineering/database-schema-designer)
  • Security penetration testing beyond input sanitization checks (see engineering/skill-security-auditor)

Integration Points

SkillIntegrationData Flow
engineering/api-design-reviewerValidate API design before generating testsDesign review output defines the endpoint contracts that this skill generates tests for
engineering/ci-cd-pipeline-builderEmbed generated tests into CI/CD pipelinesGenerated test files and k6 scripts are added as pipeline stages with pass/fail gates
engineering/playwright-proComplement API tests with E2E browser testsAPI test suite validates backend behavior; Playwright tests validate the frontend consuming those APIs
engineering/database-schema-designerAlign test fixtures with database schemaSchema definitions inform factory functions and seed data used in generated test helpers
engineering/observability-designerMonitor test-covered endpoints in productionLoad test thresholds (P95, P99) feed into alerting rules for the same endpoints in production dashboards
engineering/performance-profilerInvestigate endpoints that fail load test thresholdsk6 results identify slow endpoints; the profiler skill traces root causes at the code level