Angular 6+单元测试中的spyOn isDevMode()？

import { TestBed } from '@angular/core/testing';
import { AppComponent } from './app.component';

describe('AppComponent', () => {
  beforeEach(async () => {
    await TestBed.configureTestingModule({
      declarations: [AppComponent]
    }).compileComponents();
  });

  it('should create the app in development mode', () => {
    spyOn(console, 'log'); // Spy on console.log to check the output

    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.componentInstance;
    fixture.detectChanges();

    expect(app).toBeTruthy();
    expect(console.log).toHaveBeenCalledWith('Running in development mode');
  });

  it('should create the app in production mode', () => {
    spyOn(console, 'log'); // Spy on console.log to check the output
    spyOn(window, 'isDevMode').and.returnValue(false); // Set isDevMode() to false

    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.componentInstance;
    fixture.detectChanges();

    expect(app).toBeTruthy();
    expect(console.log).toHaveBeenCalledWith('Running in production mode');
  });
});