Sometimes you just need some configuration or module that is loaded for all your Angular test. In my case this was an injection token I wanted to set for all tests (because they were using a library). But this works just as well for any module, service, etc. you might want to add to all tests - e.g. global mock for backend services, http clients, etc.

Here are the snippets for Jest and Karma how to add such a module / configuration.

Jest

In your jest.setup.ts/js

import 'jest-preset-angular';
defineGlobalsInjections({
    imports: [YourTestingModule],
    providers: [{ provide: YOUR_TOKEN, useValue: 'yourValue' }],
});

Karma

In your test.ts/js where you call your setup with initTestEnvironment

@NgModule({
    imports: [YourTestingModule],
    providers: [{ provide: YOUR_TOKEN, useValue: 'yourValue' }],
})
class GlobalTestingSetupModule {}

TestBed.resetTestEnvironment();
TestBed.initTestEnvironment([BrowserDynamicTestingModule, GlobalTestingSetupModule], platformBrowserDynamicTesting(), {});