import { TestBed, async } from '@angular/core/testing';
import { RouterTestingModule } from '@angular/router/testing';

import { AppComponent } from './app.component';

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

  it('should create the app', async(() => {
    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.debugElement.componentInstance;
    expect(app).toBeTruthy();
  }));

  it(`should have as title 'app works!'`, async(() => {
    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.debugElement.componentInstance;
    expect(app.title).toEqual('app works!');
  }));

  it('should render title in a h1 tag', async(() => {
    const fixture = TestBed.createComponent(AppComponent);
    fixture.detectChanges();
    const compiled = fixture.debugElement.nativeElement;
    expect(compiled.querySelector('h1').textContent).toContain('app works!');
  }));
});

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

import { AppComponent } from './app.component';

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

  it('should create the app', async(() => {
    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.debugElement.componentInstance;
    expect(app).toBeTruthy();
  }));

  it(`should have as title 'app works!'`, async(() => {
    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.debugElement.componentInstance;
    expect(app.title).toEqual('app works!');
  }));

  it('should render title in a h1 tag', async(() => {
    const fixture = TestBed.createComponent(AppComponent);
    fixture.detectChanges();
    const compiled = fixture.debugElement.nativeElement;
    expect(compiled.querySelector('h1').textContent).toContain('app works!');
  }));
});

--- 
+++ 
@@ -1,4 +1,5 @@
 import { TestBed, async } from '@angular/core/testing';
+import { RouterTestingModule } from '@angular/router/testing';
 
 import { AppComponent } from './app.component';
 
@@ -8,6 +9,9 @@
       declarations: [
         AppComponent
       ],
+      imports: [
+        RouterTestingModule
+      ]
     }).compileComponents();
   }));
 
Fix to the "router-outlet is not a known element" problem.
