Fix Angular 2 Tests with Karma

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,