--- title: "@std/expect" description: "Jest compatible `expect` assertion functions" jsr: jsr:@std/expect pkg: expect version: 1.0.18 generated: true stability: stable --- ## Overview

This module provides Jest compatible expect assertion functionality.

```js import { expect } from "@std/expect"; const x = 6 * 7; expect(x).toEqual(42); expect(x).not.toEqual(0); await expect(Promise.resolve(x)).resolves.toEqual(42); ```

Currently this module supports the following functions:

Common matchers:
- toBe
- toEqual
- toStrictEqual
- toMatch
- toMatchObject
- toBeDefined
- toBeUndefined
- toBeNull
- toBeNaN
- toBeTruthy
- toBeFalsy
- toContain
- toContainEqual
- toHaveLength
- toBeGreaterThan
- toBeGreaterThanOrEqual
- toBeLessThan
- toBeLessThanOrEqual
- toBeCloseTo
- toBeInstanceOf
- toThrow
- toHaveProperty
- toMatchSnapshot
- toMatchInlineSnapshot
Mock related matchers:
- toHaveBeenCalled
- toHaveBeenCalledTimes
- toHaveBeenCalledWith
- toHaveBeenLastCalledWith
- toHaveBeenNthCalledWith
- toHaveReturned
- toHaveReturnedTimes
- toHaveReturnedWith
- toHaveLastReturnedWith
- toHaveNthReturnedWith
Asymmetric matchers:
Utilities:
- expect.addSnapshotSerializer
- expect.assertions
- expect.addEqualityTester
- expect.extend
- expect.hasAssertions

Only these functions are still not available:

Matchers:
- toThrowErrorMatchingSnapshot
- toThrowErrorMatchingInlineSnapshot

The tracking issue to add support for unsupported parts of the API is https://github.com/denoland/std/issues/3964.

This module is largely inspired by x/expect module by Allain Lalonde.

### Add to your project ```sh deno add jsr:@std/expect ``` See all symbols in @std/expect on