Skip to content
Vitest 0
Main Navigation GuideAPIConfigAdvanced
1.6.1
0.34.6

English

简体中文
繁體中文
Español
Français
Русский
Português – Brasil
Deutsch
日本語
한국어
Italiano
Polski
Türkçe
čeština
magyar

English

简体中文
繁體中文
Español
Français
Русский
Português – Brasil
Deutsch
日本語
한국어
Italiano
Polski
Türkçe
čeština
magyar

Appearance

Sidebar Navigation

Guide

Why Vitest

Getting Started

Features

Workspace

CLI

Test Filtering

Coverage

Snapshot

Mocking

Testing Types

Vitest UI

Browser Mode

In-source Testing

Test Context

Environment

Extending Matchers

IDE Integration

Debugging

Comparisons

Migration Guide

Common Errors

API

Test API Reference

Mock Functions

Vi Utility

Expect

ExpectTypeOf

assertType

Config

Config Reference

On this page

assertType ​

  • Type: <T>(value: T): void

You can use this function as an alternative for expectTypeOf to easily assert that the argument type is equal to the generic provided.

ts
import { assertType } from 'vitest';

function concat(a: string, b: string): string;
function concat(a: number, b: number): number;
function concat(a: string | number, b: string | number): string | number;

assertType<string>(concat('a', 'b'));
assertType<number>(concat(1, 2));
// @ts-expect-error wrong types
assertType(concat('a', 2));
Pager
Previous pageExpectTypeOf
Next pageConfig Reference

Released under the MIT License.

Copyright (c) 2021-Present Vitest Team

https://v0.vitest.dev/api/assert-type

Released under the MIT License.

Copyright (c) 2021-Present Vitest Team