Found the synthetic property @enterAnimation. Please include either "BrowserAnimationsModule" or "NoopAnimationsModule" in your application. Angular4

Future readers: you can also get this exact error, when you forget to place

animations: [ <yourAnimationMethod()> ]

on your @Component ts file.

that is if you're using [@yourAnimationMethod] on the HTML template.

I found the solution. I just needed to import in app.component.spec.ts the same import

 // animation module
        import { BrowserAnimationsModule } from '@angular/platform-browser/animations'; 
    ...
@NgModule({
    imports: [...
        BrowserAnimationsModule,
        ...
      ],

For my Angular 6 application, I resolved the issue by adding the following to my component .spec.ts file:

import { BrowserAnimationsModule } from '@angular/platform-browser/animations';

Then add the BrowserAnimationsModule to the imports of the TestBed.configureTestingModule in the same component .spec.ts file

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [ LinkedSitesComponent ], imports: [ BrowserAnimationsModule ],
    })
    .compileComponents();
  }));