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    api-contract-tester

    by Samuel Rose

    Turn OpenAPI specs into exhaustive, framework-ready test suites covering happy paths, edge cases, and security gaps.

    Updated Jun 2026
    243 views
    Security scanned

    $5

    · or 25 credits

    30-day refund guarantee

    Secure checkout via Stripe

    Also available in a bundle

    Included in download

    • Generate framework-ready test suites from OpenAPI specifications
    • Identify boundary conditions and off-by-one errors in API endpoints
    • browser, network automation included
    • Ready for Claude Code
    • Instant install

    Sample input

    I need to test the user registration endpoint at /v1/users. Can you generate some Jest tests to validate the request body, specifically focusing on email validation errors?

    Sample output

    "test_user_registration_invalid_email": it("returns 422 when email is missing '@'", async () => { const res = await request(app).post("/v1/users").send({ email: "bad-email" }); expect(res.status).toBe(422); expect(res.body.errors).toContainEqual(expect.objectContaining({ field: "email" })); });

    About This Skill

    Exhaustive API Contract & Regression Testing

    Transform your OpenAPI specs or Postman collections into professional-grade test suites. Unlike basic tools that only check for "200 OK" responses, this skill acts as a senior quality engineer to probe the boundaries of your API. It identifies off-by-one errors, authentication vulnerabilities, and schema mismatches before they reach production.

    What it does

    • Parse & Analyze: Extracts endpoints, schemas, and constraints from OpenAPI/Swagger, Postman, or raw code.
    • Constraint Testing: Generates tests for min/max values, regex patterns, and enum boundaries.
    • Security First: Automatically builds suites for missing tokens, malformed JWTs, and unauthorized cross-user access.
    • Robust Validation: Checks for breaking changes between versions, including field removals and type shifts.
    • Framework Flexibility: Generates code for Jest, Pytest, Vitest, Playwright, or curl scripts.

    Why use this skill

    Writing comprehensive API tests is tedious and manual. This skill automates the creation of "the tests developers forget"—such as testing rate-limit headers, pagination boundaries, and SQL injection strings. It ensures consistent error response formats and prevents internal stack traces from leaking to users. The result is a production-ready test suite with a detailed coverage report across 10 distinct categories.

    Supported Outputs

    • JavaScript/TypeScript: Jest, Vitest, Supertest, Playwright.
    • Python: Pytest with requests or httpx.
    • DevOps: Shell scripts using curl with assertions.
    • Reporting: Markdown-based coverage reports across happy paths, auth, and edge cases.

    Use Cases

    • Generate framework-ready test suites from OpenAPI specifications
    • Identify boundary conditions and off-by-one errors in API endpoints
    • Detect authentication vulnerabilities and security gaps in contract logic
    • Verify schema compliance against production-ready regression suites

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    Security Scanned

    Passed automated security review

    Permissions

    Browser
    Network Access

    Claude Code, Cursor, Windsurf, GitHub Copilot CLI, or any agent following the SKILL.md specification.

    Creator

    Founder of Agensi

    Frequently Asked Questions

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