angular/angular · error · Error

ProxyZoneSpec is needed for the fakeAsync and waitForAsync t

Error message

ProxyZoneSpec is needed for the fakeAsync and waitForAsync test helpers but could not be found. Make sure that your environment includes zone-testing.js

What it means

Error "ProxyZoneSpec is needed for the fakeAsync and waitForAsync test helpers but could not be found. Make sure that your environment includes zone-testing.js" thrown in angular/angular.

Source

Thrown at packages/zone.js/lib/zone-spec/proxy.ts:20

 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.dev/license
 */

import {ZoneType} from '../zone-impl';

declare let jest: any;

export function throwProxyZoneError(): never {
  const jestPatched = typeof jest !== 'undefined' && jest['__zone_patch__'];
  if (jestPatched) {
    throw new Error(
      'Only globals are patched with zone-testing. If you import `it`, `describe`, etc. directly, you cannot use `fakeAsync` or `waitForAsync`.',
    );
  } else {
    throw new Error(
      'ProxyZoneSpec is needed for the fakeAsync and waitForAsync test helpers but could not be found. ' +
        'Make sure that your environment includes zone-testing.js',
    );
  }
}

export class ProxyZoneSpec implements ZoneSpec {
  name: string = 'ProxyZone';

  private _delegateSpec: ZoneSpec | null = null;

  properties: {[k: string]: any} = {'ProxyZoneSpec': this};
  propertyKeys: string[] | null = null;

  lastTaskState: HasTaskState | null = null;
  isNeedToTriggerHasTask = false;

  private tasks: Task[] = [];

View on GitHub (pinned to 51cb07e980)

Solutions

1. Add zone-testing.js to the test setup files.

When it happens

Trigger: Thrown at packages/zone.js/lib/zone-spec/proxy.ts:20 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of angular/angular@51cb07e980 (2026-08-22). Data as JSON: /api/errors/0d905f658a3bfd2d. Report an issue: GitHub.