method Assert.prototype.rejects
Assert.prototype.rejects(
promise: unknown,
expectedInput?: unknown,
assertionMessage?: string
): Promise<void>

Asserts that a promise rejects. Optionally validates the rejection reason against a string (message substring), RegExp (message pattern), or constructor (instanceof check). For synchronous throws use Assert.prototype.throws.

Examples

Example 1

await assert.rejects(Promise.reject(new Error("oops")));
await assert.rejects(fetch("/bad-url"), TypeError);
await assert.rejects(Promise.reject(new Error("timeout")), /timeout/);

Parameters

promise: unknown

A promise expected to reject.

optional
expectedInput: unknown
optional
assertionMessage: string

Return Type

Promise<void>

Usage

import { Assert } from ".";