Fluent-Faker

Overview

A library for generating data in a simple way for testing

Faker is used for fake data generation

Getting Started

Install

Install it as a Dev Dependency using your favorite package manager

npm install @maarkis/fluent-faker --save-dev

or

pnpm install @maarkis/fluent-faker --save-dev

or

yarn add @maarkis/fluent-faker --dev

Usage

interface Todo {
    id: number,
    name: string,
    description: string,
    done: boolean,
}

import {createBuilder} from '@maarkis/fluent-faker'

// unique instance
createBuilder<Todo>({id: 1, name: 'Todo 1'}).generate() // { id: 1, name: 'Todo 1' }

// using faker
createBuilder<Todo>((faker) = (
    {
        id: faker.number.int(),
        name: faker.lorem.word()
    }))
    .generate() // { id: 654, name: 'eaque' }

import {generate} from '@maarkis/fluent-faker'

// unique instance
generate<Todo>({id: 1, name: 'Todo 1'}) // { id: 1, name: 'Todo 1' }

// unique instance
generate<Todo>({id: 1, name: 'Todo 1'}, 2)
// [{ id: 1, name: 'Todo 1' },{ id: 1, name: 'Todo 1' }]

Switching locales

By default, fluent-faker uses the default locale of Faker.js (en) when constructing new instances of the Builder.

You can change the locale by providing the locale parameter during the construction of the Builder class.

import {Builder} from '@maarkis/fluent-faker'

new Builder<Todo>('pt_BR')

Check Available locales in Faker.js documentation.

Using seed

Sets the seed or generates a new one

Please note that generated values are dependent on both the seed and the number of calls that have been made since it was set

This method is intended to allow for consistent values in a tests, so you might want to use hardcoded values as the seed

Global:

import {useSeed} from '@maarkis/fluent-faker'

useSeed(596) // 596

global scope, values modify Faker.js lib

Local:

import {Builder} from '@maarkis/fluent-faker'

new Builder<Todo>().useSeed(596) // 596

API Reference

createBuilder

Parameters:

Name	Type	Description	required
model	Partial<T> / Function	Initial setup for the builder	no
locale	string	The locale to set	no

Returns: new Builder instance

Usage:

import {createBuilder} from "@maarkis/fluent-faker";

createBuilder<Todo>({ id: 1, name: 'Todo 1' })

or

import {createBuilder} from "@maarkis/fluent-faker";

createBuilder<Todo>((faker) => ({
    id: faker.number.int(),
    name: 'Todo 1'
}))

or

import {createBuilder} from "@maarkis/fluent-faker";

createBuilder<Todo>(() => ({ id: 1, name: 'Todo 1' }), 'pt_BR')

---

generate

Parameters:

Name	Type	Description	required
model	Partial<T> / Function	Initial setup for the builder	no
length	number	The locale to set	no

Returns: new T instance or collection

Usage:

import {generate} from "@maarkis/fluent-faker";

generate<Todo>({ id: 1, name: 'Todo 1'}) // { id: 1, name: 'Todo 1' }

or

import {generate} from "@maarkis/fluent-faker";

generate<Todo>((faker) => ({
    id: faker.number.int(),
    name: 'Todo 1'
})) // { id: 8874, name: 'Todo 1' }

or

import {generate} from "@maarkis/fluent-faker";

generate<Todo>((faker) => ({
    id: faker.number.int(),
    name: 'Todo 1'
}), 2) // [{ id: 8874, name: 'Todo 1' },{ id: 97856, name: 'Todo 1' }]

Builder

addModel

Parameters:

Name	Type	Description	required
model	Partial<T> / Function	Defines a set of rules.	yes

Returns: Builder instance

Usage:

new Builder<Todo>()
    .addModel({id: 1, name: 'Todo 1'})
    .generate() // { id: 1, name: 'Todo 1' }

or

new Builder<Todo>()
    .addModel((faker) => ({
        id: faker.number.int(),
        name: 'Todo 1'
    }))
    .generate() // { id: 9763, name: 'Todo 1' }

---

addSet

Parameters:

Name	Type	Description	required
name	string	The set name	yes
dataSet	Partial<T> / Function	The dataset to apply when the set is specified	yes

Returns: Builder instance

Usage:

new Builder<Todo>()
    .addSet('todo done', {id: 1, name: 'Todo 1', done: true})
    .useSet('todo done')
    .generate() // { id: 1, name: 'Todo 1', done: true }

or

new Builder<Todo>()
    .addSet('todo done', (faker) => ({
        id: faker.number.int(),
        name: 'Todo 1',
        done: true
    }))
    .useSet('todo done')
    .generate() // { id: 9763, name: 'Todo 1', done: true }

---

clone

Description: Clone hte internal state into a new so that both are isolated from each other

Returns: new Builder instance

Usage:

new Builder<Todo>().clone()

---

generate

Parameters:

Name	Type	Description	required	note
length	number	The number of instances to spawn	no	If you don't pass a length, only one entity will be generated.

Returns: T instance or collection of T

Usage:

new Builder<Todo>()
    .addModel({id: 1, name: 'Todo 1'})
    .generate() // { id: 1, name: 'Todo 1' }

or

new Builder<Todo>()
    .addModel({id: 1, name: 'Todo 1'})
    .generate(2) // [{ id: 1, name: 'Todo 1' }, { id: 1, name: 'Todo 1' }]

---

ruleFor

Parameters:

Name	Type	Description	required
property	P extends keyof T / string	Property of an entity	yes
valueFunction	T[keyof T] / Function	Value of a property	yes

Returns: Builder instance

Usage:

new Builder<Todo>()
    .ruleFor('id', 1)
    .generate() // { id: 1 }

or

new Builder<Todo>()
    .ruleFor('id', () => 1)
    .generate() // { id: 1 }

or

new Builder<Todo>()
    .ruleFor('id', (faker) => faker.number.int())
    .generate() // { id: 1564 }

---

useSeed

Parameters:

Name	Type	Description	required
seed	number	The seed to set	yes

Returns: number

Usage:

new Builder<Todo>().useSeed(1) // 1

---

useSet

Parameters:

Name	Type	Description
name	string	The set name

Returns: Builder instance

Usage:

new Builder<Todo>()
    .addSet('todo done', {id: 1, name: 'Todo 1', done: true})
    .useSet('todo done')

or

new Builder<Todo>()
    .addSet('todo done', (faker) => ({
        id: faker.number.int(),
        name: 'Todo 1',
        done: true
    }))
    .useSet('todo done')