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Module

std/testing/asserts.ts>assertRejects

The Deno Standard Library
denoland/deno_std
Latest
function assertRejects
import { assertRejects } from "https://deno.land/std@0.223.0/testing/asserts.ts";

Executes a function which returns a promise, expecting it to reject.

Examples

Example 1

import { assertRejects } from "https://deno.land/std@0.223.0/testing/asserts.ts";

await assertRejects(async () => Promise.reject(new Error())); // Doesn't throw
await assertRejects(async () => console.log("Hello world")); // Throws

Parameters

fn: () => PromiseLike<unknown>
optional
msg: string

Returns

Promise<unknown>

Executes a function which returns a promise, expecting it to reject. If it does not, then it throws. An error class and a string that should be included in the error message can also be asserted.

Examples

Example 1

import { assertRejects } from "https://deno.land/std@0.223.0/testing/asserts.ts";

await assertRejects(async () => Promise.reject(new Error()), Error); // Doesn't throw
await assertRejects(async () => Promise.reject(new Error()), SyntaxError); // Throws

Type Parameters

optional
E extends Error = Error

Parameters

fn: () => PromiseLike<unknown>
ErrorClass: new (...args: any[]) => E
optional
msgIncludes: string
optional
msg: string

Returns

Promise<E>