自定义验证器FormGroup的Angular单元测试

import { TestBed } from '@angular/core/testing';
import { FormGroup, FormControl } from '@angular/forms';

import { CustomValidator } from './custom-validator';

describe('CustomValidator', () => {
  let formGroup: FormGroup;

  beforeEach(() => {
    TestBed.configureTestingModule({});
    formGroup = new FormGroup({
      username: new FormControl(''),
      password: new FormControl('')
    });
  });

  it('should return null if username is valid', () => {
    formGroup.controls['username'].setValue('john');
    const validatorFn = CustomValidator.usernameValidator();
    const result = validatorFn(formGroup.controls['username']);
    expect(result).toBeNull();
  });

  it('should return an error object if username is invalid', () => {
    formGroup.controls['username'].setValue('admin');
    const validatorFn = CustomValidator.usernameValidator();
    const result = validatorFn(formGroup.controls['username']);
    expect(result).toEqual({ invalidUsername: true });
  });
});