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

1npm install --save-dev zod-schema-faker

Usage

Built-in zod types:

1import { z } from 'zod'
2import { install, fake } from 'zod-schema-faker'
3
4// define a zod schema
5const schema = z.number()
6
7// call install() to register fakers
8install()
9
10// generate fake data based on schema
11const data = fake(schema)

Custom zod types:

1import { z } from 'zod'
2import { installCustom, fake, getFaker, ZodTypeFaker } from 'zod-schema-faker'
3
4// define a custom zod schema
5const pxSchema = z.custom<`${number}px`>(val => {
6  return typeof val === 'string' ? /^\d+px$/.test(val) : false
7})
8
9// define a custom faker
10class ZodPxFaker extends ZodTypeFaker<typeof pxSchema> {
11  fake(): `${number}px` {
12    return `${getFaker().number.int({ min: 0 })}px`
13  }
14}
15
16// call installCustom() to register custom fakers
17installCustom(pxSchema, ZodPxFaker)
18
19// generate fake data based on schema
20const data = fake(pxSchema)

API

Core APIs

• function install(): void: Install fakers for built-in types, must be called before using fake.
• function fake<T extends z.ZodType>(schema: T): z.infer<T>: Generate fake data based on schema.
• function seed(value?: number): void: Sets the seed to use.
• class ZodSchemaFakerError

Random Utility APIs

• function setFaker(faker: Faker): void: Use given faker instance instead of the default one.
• function getFaker(): Faker: Get the faker instance. Defaults to fakerEN.
• function randexp(pattern: string | RegExp, flags?: string): string: Create random strings that match a given regular expression.

Customization APIs - see example for details

• class ZodTypeFaker: Base class for fakers.
• function installCustom<T extends z.ZodTypeAny>(schema: T, faker: typeof ZodTypeFakerConcrete<T>): void: Install fakers for custom schemas, must be called before using fake.

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). ↩