Hefty

Easy, unopinionated and intuitive Typescript fixtures.

Installation

npm install hefty --save-dev

Usage

Hefty lets you create factories, chain multiple states and override those states too. Check out the tests for more examples.

Create a Factory

Factories are made up of entities with one or more states applied to them. States are called with the same params you get with Array.map().

// User.ts
class User {
  email: string
  emailConfirmed: boolean
  onboarded: boolean
}

// UserFactory.ts
import { Factory } from 'hefty'

class UserFactory extends Factory<User> {
  constructor() {
    super(User)
  }

  hasConfirmed(): this {
    return this.state(() => ({
      emailConfirmed: true
    }))
  }

  hasOnboarded(): this {
    return this.state(() => ({
      onboarded: true
    }))
  }
}

Create some users

const factory = new UserFactory()

const user1: User = await factory.one()
// -> emailConfirmed = false

const user2: User = await factory.emailConfirmed().one()
// -> emailConfirmed = true

const user3: User = await factory.emailConfirmed().onboarded().one()
// -> emailConfirmed = true, onboarded = true

const user4: User = await factory.emailConfirmed().state(() => ({ email: [email protected] })).one()
// -> emailConfirmed = true, email = [email protected]

const users: User[] = await factory.emailConfirmed().many(3)
// -> generates 3 users with emailConfirmed = true

State functions defined in the factory and state() can be chained as many times as you like in any order. They'll all be applied sequentially when one() or many() is called.

Factories with default states

Factories can implement a definition() function that is called before any other states are applied.

export default class UserFactory extends Factory<User> {
  constructor() {
    super(User)
  }

  protected definition(): void {
    this.state(() => {
      createdAt: 'today',
      emailConfirmed: true
    })
  }

  onboarded(): this {
    return this.state(() => ({
      onboarded: true
    }))
  }

  emailConfirmed(): this {
    return this.state(() => ({
      emailConfirmed: true
    }))
  }
}

const factory = await new UserFactory().one()
// => createdAt = today, emailConfirmed: true 

Promises

Hefty will automatically resolve any promise-based state() callbacks.

export default class UserFactory extends Factory<User> {
  constructor() {
    super(User)
  }

  protected definition(): void {
    this.state(async () => ({
      password: await bcrypt.hash('password', 10)
    }))
  }
}

Constructors

You can pass constructor params to the construct() function. Entities will be initialised with these params before the definition is applied.

// User.ts
class User {
  email: string

  constructor(email: string) {
    this.email = email
  }
}

// User.test.ts
const email = '[email protected]'
expect((await new UserFactory().construct(email).one()).email).toBe(email)