Angular / Jasmine单元测试-如果一个函数的$scope元素在被测试的函数中被清除，如何测试该函数是否被调用？

describe('TestComponent', () => {
  it('should call the function when $scope is cleared', () => {
    // 测试代码
  });
});

import { ComponentFixture, TestBed } from '@angular/core/testing';
import { TestComponent } from './test.component';

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

  beforeEach(async () => {
    await TestBed.configureTestingModule({
      declarations: [TestComponent]
    }).compileComponents();
  });

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

  it('should call the function when $scope is cleared', () => {
    // 模拟$scope被清除的情况
    component.$scope = null;

    // 调用被测试的函数
    component.testFunction();

    // 断言函数是否被调用
    expect(component.functionCalled).toBeTruthy();
  });
});