Found the synthetic property @enterAnimation. Plea

问题:

When running Karma to test my Angular4 application, I get this error Found the synthetic property @enterAnimation. Please include either "BrowserAnimationsModule" or "NoopAnimationsModule" in your application. though I already imported the module in app.module.ts

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

and in my component:

 import { Component, OnInit } from '@angular/core';
    import {
      trigger,
      state,
      style,
      animate,
      transition
    } from '@angular/animations';

    @Component({
      selector: 'app-about',
      animations: [
        trigger(
          'enterAnimation', [
            transition(':enter', [
              style({ transform: 'translateX(100%)', opacity: 0 }),
              animate('500ms', style({ transform: 'translateX(0)', opacity: 1 }))
            ]),
            transition(':leave', [
              style({ transform: 'translateX(0)', opacity: 1 }),
              animate('500ms', style({ transform: 'translateX(100%)', opacity: 0 }))
            ])
          ]
        ),
        trigger(
          'enterAnimationVetically', [
            transition(':enter', [
              style({ transform: 'translateY(100%)', opacity: 0 }),
              animate('500ms', style({ transform: 'translateY(0)', opacity: 1 }))
            ]),
            transition(':leave', [
              style({ transform: 'translateY(0)', opacity: 1 }),
              animate('500ms', style({ transform: 'translateY(100%)', opacity: 0 }))
            ])]
        )
      ],
...

The application runs perfectly with ng serve yet, I got this error with karma.

回答1:

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,
        ...
      ],

回答2:

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

animations: [ <yourAnimationMethod()> ]

on your @Component ts file.

that is if your'e using [@yourAnimationMethod] on the HTML template.

回答3:

For angular 7 and previous versión, you only need to add this line in your app.module.ts file, and remember put it on imports array modules too in the same file:

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

回答4:

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();
  }));