ᯓ𝘁𝗿𝗮𝘃𝗲𝗿𝘀𝗮𝗯𝗹𝗲/𝘇𝗼𝗱-𝘁𝗲𝘀𝘁

Testing utility that generates arbitrary, pseudorandom zod schemas, powered by fast-check

       

     

Requirements

@traversable/zod-test has 2 peer dependencies:

1. zod (v4)
2. fast-check

Usage

$ pnpm add -D @traversable/zod-test zod fast-check
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Here's an example of importing the library:

import { z } from 'zod'
import { zxTest } from '@traversable/zod-test'

// see below for specifc examples
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Table of contents

• zxTest.SeedGenerator
• zxTest.seedToSchema
• zxTest.seedToValidData
• zxTest.seedToInvalidData

zxTest.seedToSchema

Use zxTest.seedToSchema to convert a seed generated by zxTest.SeedGenerator into a zod schema that satisfies the configuration options you specified.

Example

import { zxTest } from '@traversable/zod-test'
import * as fc from 'fast-check'

const builder = zxTest.SeedGenerator()['*']
const [mySeed] = fc.sample(builder.object, 1)

const mySchema = zxTest.seedToSchema(mySeed)
//    ^? const mySchema: z.ZodType
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zxTest.seedToValidData

Use zxTest.seedToValidData to convert a seed generated by zxTest.SeedGenerator into data that satisfies the schema that the seed represents.

Example

import { zxTest } from '@traversable/zod-test'
import * as fc from 'fast-check'

const builder = zxTest.SeedGenerator()['*']
const [mySeed] = fc.sample(builder.object, 1)

const mySchema = zxTest.seedToSchema(mySeed)
//    ^? const mySchema: z.ZodType

const validData = zxTest.seedToValidData(mySeed)

mySchema.parse(validData) // will never throw
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zxTest.seedToInvalidData

Use zxTest.seedToInvalidData to convert a seed generated by zxTest.SeedGenerator into data that does not satisfy the schema that the seed represents.

Example

import { zxTest } from '@traversable/zod-test'
import * as fc from 'fast-check'

const builder = zxTest.SeedGenerator()['*']
const [mySeed] = fc.sample(builder.object, 1)

const mySchema = zxTest.seedToSchema(mySeed)
//    ^? const mySchema: z.ZodType

const invalidData = zxTest.seedToValidData(mySeed)

mySchema.parse(invalidData) // should always throw
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zxTest.SeedGenerator

Generates a configurable, pseudo-random "seed builder".

• Use zxTest.seedToSchema to convert a seed into a zod schema
• Use zxTest.seedToValidData to convert a seed into valid data
• Use zxTest.seedToInvalidData to convert a seed into invalid data

Example

import { zxTest } from '@traversable/zod-test'
import * as fc from 'fast-check'

const builder = zxTest.SeedGenerator({
  include: ["boolean", "string", "object"],
  // 𐙘 use `include` to only include certain schema types
  exclude: ["boolean", "any"],
  // 𐙘 use `exclude` to exclude certain schema types altogether (overrides `include`)
  minDepth: 1,
  // 𐙘 use `minDepth` to control the schema's minimum depth
  //   **NOTE:** schemas can get very large!
  //   using in your CI/CD pipeline is _not_ recommended
  object: { maxKeys: 5 },
  // 𐙘 specific arbitraries are configurable by name
})

// included schemas are present as properties on your generator...
builder.string
builder.object

// ...excluded schemas are not present...
builder.boolean // 🚫 TypeError

// ...a special wildcard `"*"` property (pronounced "surprise me") is always present:
builder["*"]

/**
 * `fast-check` will generate a seed, which is a data structure containing
 * integers that represent a kind of AST.
 *
 * To use a seed, you need to pass it to an interpreter like `zxTest.seedToSchema`,
 * `zxTest.seedToValidData` or `zxTest.seedToInvalidData`:
 */

const [mySeed] = fc.sample(builder.object, 1)

const mySchema = zxTest.seedToSchema(mySeed)
//    ^? const mySchema: z.ZodType

const validData = zxTest.seedToValidData(mySeed)
//    ^? since the `mySeed` was also used to generate `mySchema`,
//       parsing `validData` should always succeed

const invalidData = zxTest.seedToInvalidData(mySeed)
//    ^? since the `mySeed` was also used to generate `mySchema`,
//       parsing `invalidData` should always fail
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Track record

zxTest.SeedGenerator has found several upstream bugs in zod/core:

1. Bug: z.object prototype pollution bug

• Issue
• Sandbox

2. Bug: z.literal escaping bug

• Issue
• Sandbox

3. Bug: z.core.File type incompatible with globalThis.File

• Issue
• Sandbox