MockMaster 🎭

Type-safe API mocking with record & replay. Fully deterministic.

mockmaster lets you capture real API responses and replay them deterministically. Perfect for testing, offline development, and reliable demos.

Why mockmaster?

• 🔒 Type Safe - Full TypeScript support with strict typing
• 🎬 Record & Replay - Capture production API responses once, replay forever
• 📝 OpenAPI Integration - Generate mocks from OpenAPI 3.0 specs (JSON & YAML)
• 🏭 Realistic Data - Built-in factories with Faker.js for authentic test data
• 💾 Version Control - Store scenarios as JSON, commit with your code
• 🧪 Framework Agnostic - Works with Vitest, Jest, Playwright, any test framework

Quick Start

npm install @mockmaster/openapi @mockmaster/cli @mockmaster/msw-adapter

import { parseYaml } from '@mockmaster/openapi'
import { generateScenariosFromSpec, writeScenario } from '@mockmaster/cli'
import { createReplayHandler } from '@mockmaster/msw-adapter'

// 1. Parse your OpenAPI spec
const spec = parseYaml(`
openapi: 3.0.0
info:
  title: User API
  version: 1.0.0
paths:
  /users:
    get:
      responses:
        '200':
          content:
            application/json:
              schema:
                type: array
                items:
                  type: object
                  properties:
                    id: { type: integer }
                    name: { type: string }
                    email: { type: string, format: email }
`)

// 2. Generate scenarios with realistic mock data
const scenarios = generateScenariosFromSpec(spec, 'user-api')

// 3. Save to disk (commit these with your tests!)
await writeScenario('./scenarios', scenarios[0])

// 4. Replay in your tests
const handler = createReplayHandler(scenarios[0])
const response = handler({ method: 'GET', path: '/users' })
console.log(response.body) // Array of users with realistic data

Use Cases

• Testing - Deterministic API responses for reliable tests
• Offline Development - Work without network access
• CI/CD - Fast tests that don't hit real APIs
• Storybook - Develop UI components with realistic data
• Demos - Present apps without backend dependencies
• Contract Testing - Validate against OpenAPI specs

Packages

Package	Description
@mockmaster/core	Path matching & HTTP routing
@mockmaster/data	Factories & Faker integration
@mockmaster/openapi	OpenAPI parsing & generation
@mockmaster/msw-adapter	Record & replay engine
@mockmaster/cli	File system operations

Examples

Record & Replay

import { createScenario, createRecording, addRecordingToScenario } from '@mockmaster/msw-adapter'
import { writeScenario, readScenario } from '@mockmaster/cli'

// Create a scenario
let scenario = createScenario('my-api', 'Production responses')

// Add recorded responses
const recording = createRecording(
  { method: 'GET', url: 'https://api.example.com/users', path: '/users', timestamp: Date.now() },
  { status: 200, body: [{ id: 1, name: 'John' }], timestamp: Date.now() }
)
scenario = addRecordingToScenario(scenario, recording)

// Save to disk
await writeScenario('./scenarios', scenario)

// Later, load and replay
const loaded = await readScenario('./scenarios', 'my-api')
const handler = createReplayHandler(loaded)
const response = handler({ method: 'GET', path: '/users' })

Factory System

import { defineFactory, build, fake } from '@mockmaster/data'

// Define a factory
const userFactory = defineFactory('user', {
  id: (ctx) => ctx.sequence('user'),
  name: () => fake.person.fullName(),
  email: () => fake.internet.email(),
  role: () => fake.helpers.arrayElement(['admin', 'user']),
})

// Generate test data
const user1 = build(userFactory) // { id: 1, name: 'John Doe', ... }
const user2 = build(userFactory) // { id: 2, name: 'Jane Smith', ... }

// Override specific fields
const admin = build(userFactory, { overrides: { role: 'admin' } })

OpenAPI Integration

import { parseSpec, getAllOperations, generateFromSchema } from '@mockmaster/openapi'

const spec = parseSpec(yourOpenAPISpec)

// Extract all API operations
const operations = getAllOperations(spec)

// Generate mock data from schema
const mockData = generateFromSchema({
  type: 'object',
  properties: {
    id: { type: 'integer' },
    email: { type: 'string', format: 'email' },
  },
})

Development

See CONTRIBUTING.md for development setup and guidelines.

# Install dependencies
pnpm install

# Run tests
pnpm test

# Build packages
pnpm build

Roadmap

• MSW browser/Node.js integration
• Interactive CLI commands
• Middleware system
• Plugin architecture
• Visual UI dashboard
• GraphQL support

Contributing

Contributions welcome! See CONTRIBUTING.md for guidelines.

License

MIT © PxPerfectMike