如何为我的angular2表单编写使用香菜验证的jasmine单元测试？

npm install -g @angular/cli jasmine-core karma karma-chrome-launcher --save-dev

import { Component } from '@angular/core';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';
import { CupertinoValidators } from '@angular/forms/src/validators/cupertino-validators';

@Component({
  selector: 'app-form',
  template: `
    <form [formGroup]="form">
      <input formControlName="name" type="text">
      <button [disabled]="!form.valid">Submit</button>
    </form>
  `
})
export class FormComponent {
  form: FormGroup;

  constructor(private fb: FormBuilder) {
    this.form = this.fb.group({
      name: ['', [Validators.required, CupertinoValidators.min(3)]]
    });
  }
}

import { ComponentFixture, TestBed } from '@angular/core/testing';
import { ReactiveFormsModule } from '@angular/forms';
import { FormComponent } from './form.component';

describe('FormComponent', () => {
  let component: FormComponent;
  let fixture: ComponentFixture<FormComponent>;

  beforeEach(async () => {
    await TestBed.configureTestingModule({
      declarations: [FormComponent],
      imports: [ReactiveFormsModule]
    }).compileComponents();
  });

  beforeEach(() => {
    fixture = TestBed.createComponent(FormComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();
  });

  it('should create an instance of FormComponent', () => {
    expect(component).toBeTruthy();
  });

  it('form should be invalid initially', () => {
    expect(component.form.valid).toBeFalse();
  });

  it('form should be valid when name has minimum length', () => {
    component.form.controls.name.setValue('John');
    expect(component.form.valid).toBeTrue();
  });

  it('form should be invalid when name is too short', () => {
    component.form.controls.name.setValue('Jo');
    expect(component.form.valid).toBeFalse();
  });

  it('submit button should be disabled when form is invalid', () => {
    const submitButton = fixture.nativeElement.querySelector('button');
    expect(submitButton.disabled).toBeTrue();
  });

  it('submit button should be enabled when form is valid', () => {
    component.form.controls.name.setValue('John');
    fixture.detectChanges();
    const submitButton = fixture.nativeElement.querySelector('button');
    expect(submitButton.disabled).toBeFalse();
  });
});