HTTP Mocking

Nock HTTP Mocking Patterns

Critical Rule: ONLY nock for HTTP Mocking

This is a CRITICAL rule that MUST be enforced:

✅ ONLY nock is allowed for HTTP mocking ❌ NEVER use jest.mock, sinon, or fetch-mock

See failure-conditions skill Rule 4 for enforcement.

Core Principles

1. Mock at HTTP level - Mock the network request, not internal methods
2. Match requests accurately - Include method, path, headers, query params
3. Return realistic responses - Use response formats matching real API
4. Clean up after tests - Use afterEach(() => nock.cleanAll())
5. Verify mocks called - Assert expect(nock.isDone()).toBe(true)

Basic HTTP Mock Pattern

import nock from 'nock';

describe('WebhookProducer', () => {
  afterEach(() => {
    nock.cleanAll();  // Clean up after each test
  });

  it('should list webhooks successfully', async () => {
    // Mock the HTTP request
    nock('https://api.github.com')
      .get('/repos/octocat/Hello-World/hooks')
      .reply(200, [
        {
          id: '12345678',
          name: 'web',
          active: true,
          events: ['push', 'pull_request'],
          config: {
            url: 'https://example.com/webhook',
            content_type: 'json'
          },
          created_at: '2024-01-01T00:00:00Z'
        }
      ]);

    // Execute the test
    const producer = new WebhookProducer(httpClient);
    const webhooks = await producer.list('octocat', 'Hello-World');

    // Assertions
    expect(webhooks).toHaveLength(1);
    expect(webhooks[0].id).toBeDefined();
    expect(nock.isDone()).toBe(true);  // Verify mock was called
  });
});

Mock with Request Headers

nock('https://api.github.com', {
  reqheaders: {
    'Authorization': 'Bearer test-token',
    'Accept': 'application/vnd.github.v3+json'
  }
})
  .get('/repos/octocat/Hello-World/hooks')
  .reply(200, mockData);

Mock Error Responses

it('should handle 404 error', async () => {
  nock('https://api.github.com')
    .get('/repos/octocat/Hello-World/hooks/999')
    .reply(404, {
      message: 'Not Found',
      documentation_url: 'https://docs.github.com/rest'
    });

  // Test error handling
  await expect(
    producer.get('octocat', 'Hello-World', '999')
  ).rejects.toThrow(ResourceNotFoundError);

  expect(nock.isDone()).toBe(true);
});

Mock POST Request

it('should create webhook', async () => {
  const requestBody = {
    name: 'web',
    config: {
      url: 'https://example.com/webhook',
      content_type: 'json'
    },
    events: ['push'],
    active: true
  };

  nock('https://api.github.com')
    .post('/repos/octocat/Hello-World/hooks', requestBody)
    .reply(201, {
      id: '12345678',
      ...requestBody,
      created_at: '2024-01-01T00:00:00Z'
    });

  const webhook = await producer.create('octocat', 'Hello-World', config);

  expect(webhook.id).toBeDefined();
  expect(nock.isDone()).toBe(true);
});

Mock with Query Parameters

nock('https://api.github.com')
  .get('/repos/octocat/Hello-World/hooks')
  .query({ per_page: 20, page: 1 })
  .reply(200, mockData);

Reusable Mock Fixtures

// test/fixtures/webhookMocks.ts
export const mockWebhookResponse = {
  id: '12345678',
  name: 'web',
  active: true,
  events: ['push', 'pull_request'],
  config: {
    url: 'https://example.com/webhook',
    content_type: 'json'
  },
  created_at: '2024-01-01T00:00:00Z',
  updated_at: '2024-01-01T00:00:00Z'
};

export function mockListWebhooks(owner: string, repo: string, data: any[]) {
  return nock('https://api.github.com')
    .get(`/repos/${owner}/${repo}/hooks`)
    .reply(200, data);
}

Validation Checklist

# Verify ONLY nock is used
grep "from ['\"]nock['\"]" test/unit/*.ts
# Should show nock imports

# Ensure NO forbidden mocking libraries
grep -E "jest\.mock|sinon|fetch-mock" test/*.ts
# Should return nothing (exit code 1)

# Verify mock cleanup present
grep "nock.cleanAll()" test/unit/*.ts
# Should show in afterEach blocks

# Verify mock verification present
grep "nock.isDone()" test/unit/*.ts
# Should show in test assertions

Anti-Patterns: What NOT to Do

❌ WRONG: Using jest.mock

// ❌ NO! Don't mock at method level
jest.mock('./WebhookProducer');

Why wrong: Mocks internal implementation instead of HTTP layer.

❌ WRONG: Using sinon

// ❌ NO! Don't use sinon
import sinon from 'sinon';
const stub = sinon.stub(producer, 'list');

Why wrong: Not allowed - violates testing rules.

❌ WRONG: Using fetch-mock

// ❌ NO! Use nock instead
import fetchMock from 'fetch-mock';

Why wrong: Not allowed - only nock is permitted.

✅ CORRECT: Using nock

// ✅ YES! Mock at HTTP level with nock
import nock from 'nock';
nock('https://api.github.com')
  .get('/repos/octocat/Hello-World/hooks')
  .reply(200, mockData);

Why correct: Mocks at HTTP level using approved library.

Standard Output Format

When documenting HTTP mocking strategy:

# HTTP Mocking Strategy: {ProducerName}

## Mock Library
✅ **nock** (ONLY allowed library)

## Mock Patterns Created

### List Operation
```typescript
nock('https://api.github.com')
  .get('/repos/octocat/Hello-World/hooks')
  .reply(200, [mockWebhookResponse]);

Get Operation

nock('https://api.github.com')
  .get('/repos/octocat/Hello-World/hooks/12345678')
  .reply(200, mockWebhookResponse);

Error Case

nock('https://api.github.com')
  .get('/repos/octocat/Hello-World/hooks/999')
  .reply(404, { message: 'Not Found' });

Mock Cleanup

✅ afterEach(() => nock.cleanAll())

Mock Verification

✅ expect(nock.isDone()).toBe(true)

Validation

✅ Only nock used ✅ HTTP level mocking ✅ Realistic responses ✅ Proper cleanup ✅ Mock verification

## Success Criteria

HTTP mocking implementation MUST meet all criteria:

- ✅ Only nock library used (no jest.mock, sinon, fetch-mock)
- ✅ All HTTP requests mocked at network level
- ✅ Realistic mock responses (match API format)
- ✅ Proper cleanup after tests (`nock.cleanAll()`)
- ✅ Mock verification in tests (`nock.isDone()`)
- ✅ Reusable mock patterns/fixtures where appropriate
- ✅ Request matching includes method, path, headers (when relevant)