Which @angular/* package(s) are the source of the bug?

zone.js

Is this a regression?

No

Description

Description / Descripción:

This StackBlitz demonstrates a minimal Angular 20 project withzone.js@0.15.x where unit tests cannot run due to the following error:

NG0908: In this configuration Angular requires Zone.js
zone-testing.js is needed for the fakeAsync() test helper but could not be found.

The project includes a minimal AppComponent and a basic test in app.component.spec.ts.
The test.ts file imports zone.js and zone.js/testing as recommended.
All dependencies are set to the latest Angular 20 and zone.js 0.15.x versions.
How to reproduce:

Clone this project locally or use the same setup in your environment.
Run npm install and then ng test.
Observe that all tests fail with the error above.
Note:
StackBlitz may not support running ng test directly, but this code matches the setup that fails locally.

Please provide a link to a minimal reproduction of the bug

stackblitz-comeditangular-9vvkqanb-filesrc2ftest-ts

Please provide the exception or error you saw

NG0908: In this configuration Angular requires Zone.jszone-testing.js is needed for the fakeAsync() test helper but could not be found.

Please provide the environment you discovered this bug in (runng version)

Angular CLI: 20.3.4Node: 22.19.0Package Manager: npm 10.9.3OS: win32 x64    Angular: 20.3.3... common, compiler, compiler-cli, core, forms... platform-browser, platform-server, routerPackage                      Version------------------------------------@angular-devkit/architect    0.2003.4@angular-devkit/core         20.3.4@angular-devkit/schematics   20.3.4@angular/build               20.3.4@angular/cdk                 20.2.7@angular/cli                 20.3.4@angular/material            20.2.7@angular/ssr                 20.3.4@schematics/angular          20.3.4rxjs                         7.8.2typescript                   5.9.3zone.js                      0.15.1

Anything else?

No response