• 首先我们需要自定义一个组件，如下：

@Component({
  selector: 'sion-basic-select', 
  template: `
  <sino-remote-select [formControl]="control" 
  </sino-remote-select>`,
})
class BasicSelectComponent {
  control = new FormControl();

  @ViewChild(SinoRemoteSelectComponent) select: SinoRemoteSelectComponent;
}

• 然后我们可以模拟做单元测试前的初始化

  import { Component, ViewChild } from '@angular/core';
  import { ComponentFixture, TestBed, fakeAsync, tick } from '@angular/core/testing';
  import { FormControl } from '@angular/forms';
  
  import { SinoRemoteSelectComponent } from './sino-remote-select.component';
  import { SinoRemoteSelectComponent } from './sino-remote-select.component';
  
  describe('sino-remote-select: form item features', () => {
    let fixture: ComponentFixture<BasicSelectComponent>;
    let basicSelectComponent: BasicSelectComponent;
  
    beforeEach(() => {
      TestUtils.beforeEachCompiler([SinoRemoteSelectComponent, BasicSelectComponent]);
    });
  
    beforeEach(() => {
      fixture = TestBed.createComponent(BasicSelectComponent);
      basicSelectComponent = fixture.componentInstance;
    });
  

• 现在，我们先要测试当模型值发生改变时，模板值是否与模板值相等

  it('can use sino-remote-select in reactive forms', () => {
      basicSelectComponent.control = new FormControl('02');  //给模型赋值
  
      fixture.detectChanges();
  
      expect(basicSelectComponent.select.value).toBe('02');  //期望模板值与模型值相等
    });
  

• 对应的，我们需要测试当模板值改变时，模型值是否改变

  it('should update the form value when the view changes', () => {
      fixture.detectChanges();
  
      basicSelectComponent.select.value = '123';
      fixture.detectChanges();
  
      expect(basicSelectComponent.control.value).toBe('123');
    });