zod-schema-faker

Generate mock data from zod schemas. Powered by @faker-js/faker and randexp.js.

Features

• Support almost all zod types
• Support for custom zod types
• Extensive tests

Installation

npm install --save-dev zod-schema-faker

Usage

Built-in zod types:

import { z } from 'zod'
import { install, fake } from 'zod-schema-faker'

// define a zod schema
const schema = z.number()

// call install() to register fakers
install()

// generate fake data based on schema
const data = fake(schema)

Custom zod types:

import { z } from 'zod'
import { installCustom, fake, runFake, ZodTypeFaker } from 'zod-schema-faker'

// define a custom zod schema
const pxSchema = z.custom<`${number}px`>(val => {
  return typeof val === 'string' ? /^\d+px$/.test(val) : false
})

// define a custom faker
class ZodPxFaker extends ZodTypeFaker<typeof pxSchema> {
  fake(): `${number}px` {
    return `${runFake(faker => faker.number.int({ min: 0 }))}px`
  }
}

// call installCustom() to register custom fakers
installCustom(pxSchema, ZodPxFaker)

// generate fake data based on schema
const data = fake(pxSchema)

API

Core APIs

• function install(): register fakers, must be called before using fake()
• function fake(schema): generate fake data based on schema
• function seed(value): sets the seed to use
• class ZodSchemaFakerError: thrown when an error occurs, such as when a corresponding faker is not registered

Random Utility APIs

• function installFaker(faker): install a custom faker, must be called before using runFake(). defaults to fakerEN from @faker-js/faker
• function runFake(runner)
• function randexp(pattern, flags)

Customization APIs - see example for details

• class ZodTypeFaker: base class for custom fakers
• function installCustom(schema, faker): register a custom faker

Supported Zod Types

• methods
  • ✅ .and
  • ✅ .array
  • ✅ .brand
  • ✅ .catch
  • ✅ .default
  • ✅ .nullable
  • ✅ .nullish
  • ✅ .optional
  • ✅ .or
  • ✅ .pipe
  • ✅ .promise
  • ✅ .readonly
  • ❌ .refine
  • ❌ .superRefine
  • ✅ .transform
• ✅ z.any
• ✅ z.array
• ✅ z.bigint
• ✅ z.boolean
• ✅ z.custom: see example for details.
• ✅ z.date
• ✅ z.discriminatedUnion
• ✅ z.enum
• ✅ z.instanceof: see example for details.
• ✅ z.intersection
• ✅ z.function
• ✅ z.lazy
• ✅ z.literal
• ✅ z.map
• ✅ z.nan
• ✅ z.nativeEnum
• ✅ z.never: always throws an error
• ✅ z.null
• ✅ z.number
• ✅ z.object
• ✅ z.preprocess¹
• ✅ z.promise
• ✅ z.record
• ✅ z.set
• ✅ z.string²
• ✅ z.symbol
• ✅ z.tuple
• ✅ z.undefined
• ✅ z.union
• ✅ z.unknown
• ✅ z.void

Comparison

@anatine/zod-mock

https://github.com/anatine/zod-plugins/tree/main/packages/zod-mock

• Excels at generating realistic data for z.string. For instance, z.object({ image: z.string() }) will produce a URL string.
• Lacks support for some basic zod types such as z.any, z.default, z.tuple, etc.

zod-fixture

https://github.com/timdeschryver/zod-fixture

• Provides support for custom zod types.
• Occasionally generates invalid mocked data. For example, calling with the function generated from z.function(z.tuple([]), z.boolean()) did not return a boolean value.

Inactive Libraries

• https://github.com/dipasqualew/zod-mocking
• https://github.com/LorisSigrist/zocker
• https://github.com/ItMaga/zodock

About

Distributed under the MIT license. See LICENSE for more information.

Footnotes

1. Not applicable, ignored ↩

2. Not compatible with other validations. For example, z.length(5) is ignored in z.base64().length(5). ↩