jest-expect-each

A Jest extension that adds expect.each() for testing multiple values efficiently.

Overview

jest-expect-each is a Jest extension developed by Open Reach Tech Inc. that allows you to run the same assertion against multiple values in a concise and readable way.

Installation

npm install @openreachtech/jest-expect-each

Setup

Add the following line to your Jest setup file (e.g., jest.setup.js):

const setupExpectEach = require('@openreachtech/jest-expect-each')

setupExpectEach()

Or import it at the top of individual test files:

const setupExpectEach = require('@openreachtech/jest-expect-each')

setupExpectEach()

Usage

Basic Usage: Single Expected Value

Test multiple actual values against one common expected value:

test('all values should be 100', () => {
  const actualValues = [100, 100, 100, 100]
  const expectedValue = 100

  expect.each(actualValues)
    .toBe(expectedValue)
})

Advanced Usage: Multiple Expected Values

Test each actual value against its corresponding expected value:

test('values should match their multiplied results', () => {
  const actualValues = [1, 2, 3, 4].map(it => it * 100)
  const expectedValues = [100, 200, 300, 400]

  expect.each(actualValues)
    .toBe.each(expectedValues)
})

Working with Promises

Using resolves

test('all promises should resolve to expected values', async () => {
  const promises = [
    Promise.resolve(100),
    Promise.resolve(100),
    Promise.resolve(100)
  ]

  await expect.each(promises)
    .resolves
    .toBe(100)
})

Using rejects

test('all promises should reject with error', async () => {
  const promises = [
    Promise.reject(new Error('failed')),
    Promise.reject(new Error('failed'))
  ]

  await expect.each(promises)
    .rejects
    .toThrow('failed')
})

Using not Matcher

test('no value should be 999', () => {
  const actualValues = [100, 200, 300]

  expect.each(actualValues)
    .not
    .toBe(999)
})

TypeScript Support

When using TypeScript or type checking in VS Code, import types/jest-expect.each.d.ts in your package.

Error Handling

When using .each() with multiple expected values, the array lengths must match:

• If actualValues.length > expectedValues.length: throws "expect.each() received lacked array"
• If actualValues.length < expectedValues.length: throws "expect.each() received excess array"

License

This project is released under the MIT License.

See LICENSE for details.

Contributing

Bug reports, feature requests, and code contributions are welcome.

Feel free to contact us through GitHub Issues.

git clone https://github.com/openreachtech/jest-expect-each.git
cd jest-expect-each
npm install
npm run lint
npm test

Developers

Open Reach Tech Inc.

Copyright

© 2026 Open Reach Tech Inc.