Angular 2 unit testing components with routerLink

Question

I am trying to test my component with angular 2 final, but I get an error because the component uses the routerLink directive. I get the following error:

Can't bind to 'routerLink' since it isn't a known property of 'a'.

This is the relevant code of the ListComponent template

<a 
  *ngFor="let item of data.list" 
  class="box"
  routerLink="/settings/{{collectionName}}/edit/{{item._id}}">

And here is my test.

import { TestBed } from '@angular/core/testing';

import { ListComponent } from './list.component';
import { defaultData, collectionName } from '../../config';
import { initialState } from '../../reducers/reducer';


const data = {
  sort: initialState.sort,
  list: [defaultData, defaultData],
};

describe(`${collectionName} ListComponent`, () => {
  let fixture;
  beforeEach(() => {
    TestBed.configureTestingModule({
      declarations: [
        ListComponent,
      ],
    }).compileComponents(); // compile template and css;
    fixture = TestBed.createComponent(ListComponent);
    fixture.componentInstance.data = data;
    fixture.detectChanges();
  });

  it('should render 2 items in list', () => {
    const el = fixture.debugElement.nativeElement;
    expect(el.querySelectorAll('.box').length).toBe(3);
  });
});

I looked at several answers to similar questions but could not find a solution that worked for me.

Leucoderma

Answer 1

You need to configure all the routing. For testing, rather than using the RouterModule, you can use the RouterTestingModule from @angular/router/testing, where you can set up some mock routes. You will also need to import the CommonModule from @angular/common for your *ngFor. Below is a complete passing test

import { Component } from '@angular/core';
import { Router } from '@angular/router';
import { By } from '@angular/platform-browser';
import { Location, CommonModule } from '@angular/common';
import { RouterTestingModule } from '@angular/router/testing';
import { TestBed, inject, async } from '@angular/core/testing';

@Component({
  template: `
    <a routerLink="/settings/{{collName}}/edit/{{item._id}}">link</a>
    <router-outlet></router-outlet>
  `
})
class TestComponent {
  collName = 'testing';
  item = {
    _id: 1
  };
}

@Component({
  template: ''
})
class DummyComponent {
}

describe('component: TestComponent', function () {
  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [
        CommonModule,
        RouterTestingModule.withRoutes([
         { path: 'settings/:collection/edit/:item', component: DummyComponent }
        ])
      ],
      declarations: [ TestComponent, DummyComponent ]
    });
  });

  it('should go to url',
    async(inject([Router, Location], (router: Router, location: Location) => {

    let fixture = TestBed.createComponent(TestComponent);
    fixture.detectChanges();

    fixture.debugElement.query(By.css('a')).nativeElement.click();
    fixture.whenStable().then(() => {
      expect(location.path()).toEqual('/settings/testing/edit/1');
      console.log('after expect');
    });
  })));
});

UPDATE

Another option, if you just want to test that the routes are rendered correctly, without trying to navigate...

You an just import the RouterTestingModule without configuring any routes

imports: [ RouterTestingModule ]

then just check that the link is rendered with the correct URL path, e.g.

let href = fixture.debugElement.query(By.css('a')).nativeElement
    .getAttribute('href');
expect(href).toEqual('/settings/testing/edit/1');

Fourierism

Thanks, this helps already alot, but I cannot get the unit test to fail. It seems that the because of async everything in this block is ginored. I tried to add a done function to the it('...', (done) => {async(... done())} but then I get Error: Timeout from the test. – Leucoderma

My bad, I had the async wrapped in another function and not as second parameter of the it. It works now, thanks. – Leucoderma

This is fantastic. Finally found an answer that applies to 2.0 Final (I'm using 2.1)! Since I was going to need the same configuration in a lot of tests, I created a test-only module that configured RouterTestingModule and declared the DummyComponent. Then I put that module and the DummyComponent into a test/ subfolder, which I can then import into any of my unit tests. Thanks @peeskillet – Mcguire

Actually, if you only need to render routerLink you don't have to setup the routing – Mazurek

Very thorough and solid answer, thank you. Resolves all routerLink testing issues I saw. – Kunin

getAttribute('href') returns null for me, while it works in app. Is there something I miss? – Selfrespect

@Paul Samsotha do you know how to do the same with providers array? I could not get this working – Leoine

Answer 2

If you are not testing router related stuff, you can configure the test to ignore unknown directives with 'NO_ERRORS_SCHEMA'

 import { NO_ERRORS_SCHEMA } from '@angular/core';
 TestBed.configureTestingModule({
   declarations: [
     ListComponent,
   ],
   schemas: [ NO_ERRORS_SCHEMA ]
 });

Christoper

Thanks that is even a more specific solution to my problem, thoug I learned also form the first one. Could you please also share where to import NO_ERRORS_SCHEMA from. – Leucoderma

NO_ERRORS_SCHEMA is currently flagged as Experimental – Boyce

@Boyce That shouldn't matter. A lot of things are marked experimental (including commonly used classes like Http). angular.io/docs/ts/latest/api/#!?status=experimental – Bulwerlytton

You should pretty much never use NO_ERRORS_SCHEMA it does a lot more than just fix this. It also causes ALL errors to pass in tests – Highkeyed

Answer 3

To write a test case for routerLink. You can follow the below steps.

1. Import RouterTestingModule and RouterLinkWithHref.

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

2. Import RouterTestingModule in your module

   TestBed.configureTestingModule({
     imports: [ RouterTestingModule.withRoutes([])],
     declarations: [ TestingComponent ]
   })
   

3. In test case find the directive RouterLinkWithHref tot test for the existence of the link.

   it('should have a link to /', () => {
     const debugElements = fixture.debugElement.queryAll(By.directive(RouterLinkWithHref));
     const index = debugElements.findIndex(de => {
       return de.properties['href'] === '/';
     });
     expect(index).toBeGreaterThan(-1);
   });
   

Demolish

The import work also as imports: [ RouterTestingModule ] – Ioved

linkDes = fixture.debugElement.queryAll(By.directive(RouterLinkWithHref)); routerLinks = linkDes.map(de=>de.injector.get(RouterLinkWithHref)); expect(routerLinks[0].href).toBe('/settings/testing/edit/1'); – Hardaway

Answer 4

How to check that the Router actually triggered the URL change

---

Solution inspired by https://medium.com/@douglascaina/angular-tdd-how-to-test-routerlink-or-url-change-494f18208443

---

My setup (using ng-mocks):

class MockComponent {}

// ...

MockBuilder(MyComponent)
  .keep(RouterTestingModule.withRoutes([{ path: 'my/path', component: MockComponent }]))
  .keep(RouterLink)

My test case:

it('when clicked, myLinkElement should lead to /my/path', fakeAsync(() => {
  const { page, router } = setup();
  page.detectChanges();

  page.click(page.myLinkElement().nativeElement);
  tick();

  expect(router.url).toEqual('/my/path');
}));

Eberhardt