title: mat-option' is not a known element, angular4 spec.ts error
body: <p>i am trying to test a component having angular-material components.</p>
  
  <pre><code>beforeEach(async(() =&gt; {
  TestBed.configureTestingModule({
    declarations: [ serviceCategoriesComponent ],
    imports: [
      MatDatepickerModule,
      MatInputModule,
      MatIconModule,
      AngularMultiSelectModule,
      MatSlideToggleModule,
      MatPaginatorModule,
      MatSortModule,
      MatChipsModule,
      MatAutocompleteModule,
      MatTooltipModule,
      MatSelectModule,
      MatFormFieldModule,
      FormsModule,
      ReactiveFormsModule
    ]
  })
  .compileComponents();
  </code></pre>
  
  <p>}));</p>
  
  <p>These i have already imported. But I am getting error : </p>
  
  <pre><code>1. If 'mat-option' is an Angular component, then verify that it is part of this module.
      2. If 'mat-option' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.
  </code></pre>
  
  <p>Please help.</p>