Angular单元测试遇到的错误消息：Uncaught Error - Cannot find module tslib

我的单元测试源代码：

@Component({
  selector: 'cx-host',
  template: ` <div id="a" [cxFocus]="{ autofocus: true, refreshFocus: model.uid }"></div>`,
  changeDetection: ChangeDetectionStrategy.Default,
})
class MockComponent {
  model = "";
}
      

将下图import的代码改成：

from '@angular/core'