Contract Testing

What it does

When your agent uses it

• Testing API contracts
• Coordinating distributed teams

Example prompts

• “/contract-testing”

Requirements

• Node.js

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

1. 1DEFINE consumer expectations (what consumers actually need)
2. 2VERIFY provider fulfills contracts (Pact verification)
3. 3DETECT breaking changes before deployment (CI/CD integration)
4. 4VERSION APIs semantically (breaking = major bump)
5. 5MAINTAIN backward compatibility for supported versions

What it can do on your machine

Read from SKILL.md and the folder at commit 829d030. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Ships 1 file in scripts/, which the agent can run.

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Contract Testing loads about 1.8k tokens when it runs, and up to ~2.9k if it reads all its reference files. Until then it costs about 54 tokens; SKILL.md has 368 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~54

When it runs · the whole SKILL.md, loaded when a task matches

~1.8k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~2.9k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from proffesor-for-testing/agentic-qe at commit 829d030, republished under its MIT licence (© proffesor-for-testing). 368 words, ~1,807 tokens.

name

contract-testing

description

Consumer-driven contract testing for microservices using Pact, schema validation, API versioning, and backward compatibility testing. Use when testing API contracts or coordinating distributed teams.

category

testing-methodologies

priority

high

tokenEstimate

900

agents

qe-api-contract-validator, qe-test-generator, qe-security-scanner

implementation_status

optimized

optimization_version

1

last_optimized

2025-12-02

quick_reference_card

true

tags

contract, pact, consumer-driven, api, microservices, schema-validation

trust_tier

3

Consumer → Defines Expectations → Contract
                    ↓
Provider → Verifies Contract → Pass/Fail
                    ↓
CI/CD → Blocks Breaking Changes

// Consumer defines what it needs
const { Pact } = require('@pact-foundation/pact');

describe('Order API Consumer', () => {
  const provider = new Pact({
    consumer: 'CheckoutUI',
    provider: 'OrderService'
  });

  beforeAll(() => provider.setup());
  afterAll(() => provider.finalize());

  it('creates an order', async () => {
    await provider.addInteraction({
      state: 'products exist',
      uponReceiving: 'a create order request',
      withRequest: {
        method: 'POST',
        path: '/orders',
        body: { productId: 'abc', quantity: 2 }
      },
      willRespondWith: {
        status: 201,
        body: {
          orderId: like('order-123'),  // Any string matching pattern
          total: like(19.99)           // Any number
        }
      }
    });

    const response = await orderClient.create({ productId: 'abc', quantity: 2 });
    expect(response.orderId).toBeDefined();
  });
});

// Provider verifies it fulfills all consumer contracts
const { Verifier } = require('@pact-foundation/pact');

describe('Order Service Provider', () => {
  it('fulfills all consumer contracts', async () => {
    await new Verifier({
      provider: 'OrderService',
      providerBaseUrl: 'http://localhost:3000',
      pactUrls: ['./pacts/checkoutui-orderservice.json'],
      stateHandlers: {
        'products exist': async () => {
          await db.products.create({ id: 'abc', price: 9.99 });
        }
      }
    }).verifyProvider();
  });
});

// Agent detects breaking changes
await Task("Contract Validation", {
  currentContract: 'openapi-v2.yaml',
  previousContract: 'openapi-v1.yaml',
  detectBreaking: true,
  calculateSemver: true,
  generateMigrationGuide: true
}, "qe-api-contract-validator");

// Output:
// Breaking changes found: 2
// - Removed field: order.discount
// - Type change: order.total (number → string)
// Recommended version: 3.0.0 (major bump)

name: Contract Tests
on: [push]

jobs:
  consumer-tests:
    steps:
      - run: npm run test:contract
      - name: Publish Pacts
        run: npx pact-broker publish ./pacts --broker-base-url $PACT_BROKER

  provider-verification:
    needs: consumer-tests
    steps:
      - name: Verify Provider
        run: npm run verify:contracts
      - name: Can I Deploy?
        run: npx pact-broker can-i-deploy --pacticipant OrderService --version $VERSION

aqe/contract-testing/
├── contracts/*           - Current contracts
├── breaking-changes/*    - Detected breaking changes
├── versioning/*          - Version compatibility matrix
└── verification-results/* - Provider verification history

const contractFleet = await FleetManager.coordinate({
  strategy: 'contract-testing',
  agents: [
    'qe-api-contract-validator',  // Validation, breaking detection
    'qe-test-generator',          // Generate contract tests
    'qe-security-scanner'         // API security
  ],
  topology: 'sequential'
});

© proffesor-for-testing, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 6 other files (scripts, references) in assets/skills/contract-testing of proffesor-for-testing/agentic-qe.

• SKILL.md
• config.json
• evals/contract-testing.yaml
• references/agent-commands.md
• references/provider-states.md
• schemas/output.json
• scripts/validate-config.json

Open the folder on GitHubat commit 829d030