在Angular单元测试中，如果需要测试多个视图组件，可以使用TestBed.createComponent创建组件实例，通过调用fixture.detectChanges()来更新组件的视图，并使用fixture.debugElement.queryAll()来查找子组件并进行测试。下面是一个示例：

import { Component, Input } from '@angular/core';
import { ComponentFixture, TestBed } from '@angular/core/testing';

@Component({
  selector: 'app-child',
  template: '
{{title}}
',
})
class ChildComponent {
  @Input() title: string;
}

@Component({
  selector: 'app-parent',
  template: `
    
  `,
})
class ParentComponent {
  titles = ['Title 1', 'Title 2', 'Title 3'];
}

describe('ParentComponent', () => {
  let fixture: ComponentFixture;
  let parent: ParentComponent;

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

  beforeEach(() => {
    fixture = TestBed.createComponent(ParentComponent);
    parent = fixture.componentInstance;
    fixture.detectChanges();
  });

  it('should create parent component with three child components', () => {
    expect(parent).toBeTruthy();
    expect(fixture.debugElement.queryAll(By.directive(ChildComponent)).length).toBe(3);
  });

  it('should display child component titles correctly', () => {
    const childElements = fixture.debugElement.queryAll(By.directive(ChildComponent));
    childElements.forEach((childElement, index) => {
      const childComponent = childElement.componentInstance as ChildComponent;
      const titleElement = childElement.query(By.css('h1')).nativeElement;
      expect(titleElement.textContent).toEqual(parent.titles[index]);
    });
  });
});

该示例中，我们测试ParentComponent是否正确地渲染了三个ChildComponent，并测试每个ChildComponent的title是否正确显示。