角度信号访问在测试时出错

Question

我的组件上有这个新的角度信号变量：

private employees: Signal<Employee[]> = this.employeesService.filteredEmployeesSignal;
public employeesDataSource = computed(
    () => new MatTableDataSource<Employee>(this.employees())
);

一切正常，直到测试因以下错误而失败：

this.employees is not a function

当尝试访问

this.employees()

信号值时。它检测为函数而不是信号值获取器。

我尝试获取计算信号内其他局部常量的值，但错误仍然存在。

Answer 1

我们可以模拟服务并在模拟服务上配置

signal

，然后检查返回值！

规格ts

import { ComponentFixture, TestBed } from '@angular/core/testing';
import { CommonModule } from '@angular/common';
import { AppComponent } from './app.component';
import { signal } from '@angular/core';
import { EmployeesService } from './employees.service';

describe('App tests', () => {
  let component: AppComponent;
  let fixture: ComponentFixture<AppComponent>;
  let employeeServiceMock!: EmployeesService;

  beforeEach(async () => {
    employeeServiceMock = {
      filteredEmployeesSignal: signal([]),
    };
    await TestBed.configureTestingModule({
      imports: [CommonModule],
      providers: [
        {
          provide: EmployeesService,
          useValue: employeeServiceMock,
        },
      ],
    }).compileComponents();

    fixture = TestBed.createComponent(AppComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();
  });

  it('should set employees property', () => {
    expect(component['employees']()).toEqual([]);
  });
});

stackblitz 演示 ->

cd test

->

npm i

->

npm run test