🚀 MegaMock for NestJS

MegaMock is a declarative mock generator for NestJS.
It creates mock API responses directly from class definitions using decorators — no json-server, no swagger mocker, no manual fixtures.

✨ Features

• 🎯 Generate mock API responses via the @MockRoute decorator
• 🧩 Nested entities with @MockProperty({ type: User })
• 🔄 Array generation with random lengths
• ❓ Nullable fields with automatic probability
• 🧱 Depth limit to prevent circular structures
• 📦 Works with HTTP, WebSockets, tests, and local development
• 🔌 No external mock servers or JSON files required

📦 Installation

npm install @megamock/nest
# or
yarn add @megamock/nest

🚀 Quick Start

1. Create a mock DTO (not tied to ORM entities)

import { MockProperty } from '@svintsoff78/megamock';

export class UserMock {
  @MockProperty({ type: 'id' })
  id: number;

  @MockProperty({ type: 'string' })
  name: string;

  @MockProperty({ type: 'string', nullable: true })
  avatarUrl: string | null;
}

2. Nested mock entities and arrays

import { MockProperty } from '@svintsoff78/megamock';
import { UserMock } from './user.mock';

export class ChatMock {
  @MockProperty({ type: 'id' })
  id: number;

  @MockProperty({ type: 'title' })
  title: string;

  @MockProperty({
    type: UserMock,
    isArray: true,
    arrayLength: [2, 6],
  })
  participants: UserMock[];
}

3. Generate mock responses via @MockRoute

import { Controller, Get } from '@nestjs/common';
import { MockRoute } from '@megamock/nest';
import { ChatMock } from './chat.mock';

@Controller('chats')
export class ChatController {
  @Get()
  @MockRoute(ChatMock, { isArray: true, arrayLength: [3, 5] })
  findAll() {}

  @Get(':id')
  @MockRoute(ChatMock)
  findOne() {}
}

MegaMock will fully generate the response for these routes.

⚙️ MockRoute Options

@MockRoute(ChatMock, {
  isArray: true,
  arrayLength: [min, max]
})

| Option | Description | Required? | |--------------|-----------------------------------------------------|-----------| | isArray | Generate a list of entities instead of a single one | false | | arrayLength | Random array length within the provided range | false |

⚙️ MockProperty Options

@MockProperty({ 
    type: 'string',
    nullable: true,
    isArray: true,
    arrayLength: [min, max]
})

| Option | Description | Required? | |---------------|------------------------------------------------------------|-----------| | type | string, number, boolean, uuid, date, Type<any> | true | | nullable | Can the property be nullable | false | | isArray | Generate a list of entities instead of a single one | false | | arrayLength | Random array length within the provided range | false |

🧠 Why MegaMock?

• ✔ Response types always match your DTOs
• ✔ No duplicated mock JSON files
• ✔ No external mock servers
• ✔ Great for frontend-backend parallel development
• ✔ Works natively with NestJS decorators and interceptors
• ✔ Consistent and predictable data generation

🗺 Roadmap

• 🔮 Faker integration (names, emails, lorem, addresses)
• ♻ Record mode (save real responses and replay them as mocks)
• 📚 Swagger examples autogeneration
• 🎛 Custom generators for advanced scenarios
• 🧬 Fine-grained rules for nested structures
• 🎨 Playground UI for inspecting mock outputs

🤝 Contributing

Contributions are welcome! Open an issue or PR — let's build MegaMock together.

📄 License

MIT — free to use, modify, and distribute.

⭐ If MegaMock helps you — consider starring the repository!