Below are some fixes I had to apply in order to make Angular 2 tests work with karma.

Binding

  • Error: Can't bind to 'ngModel' since it isn't a known property of 'input'

  • Solution: Import FormsModulein your test:

    TestBed.configureTestingModule({
  declarations: [AppComponent],
  imports: [FormsModule]
})

Unknown component

  • Error: 'custom-component' is not a known element

  • Solution: Declare the component in your test:

    TestBed.configureTestingModule({
  declarations: [
    MyComponent,
    CustomComponent // The component declared in the template
  ]
})

Note: If the element is in another module, then import the other module (like in the previous case) instead of declaring elements one by one.

Unknown <router-outlet> tag

  • Error: 'router-outlet' is not a known element

  • Solution: Import RouterTestingModule:

    import { RouterTestingModule } from '@angular/router/testing'

// ...

TestBed.configureTestingModule({
  declarations: [AppComponent, OtherComponent],
  imports: [RouterTestingModule]
})

Note: This list contains issues I've encountered. Please feel free to send me more.

HTH,