我如何使用 ng-template 和触发它的操作来测试模式的元素？

Question

I read the Angular Testing and I'm not sure if there is any reference about testing elements inside a modal and how to check custom actions. My purpose is to write the necessary tests show I will be sure that my function and the modal works as expected.

As the modal is hidden, the tests to check if the elements of the modal appear, fail. So I suppose that there is something missing here.

This is my photos.components.ts file:

import {Component, OnInit, ViewEncapsulation} from '@angular/core';
import { NgbModal } from '@ng-bootstrap/ng-bootstrap';

@Component({
  selector: 'app-photos',
  templateUrl: './photos.component.html',
  styleUrls: ['./photos.component.scss'],
  encapsulation: ViewEncapsulation.None
})
export class PhotosComponent implements OnInit {

  constructor(private modalService: NgbModal) { }

  openDarkModal(content) {
    this.modalService.open(content, { windowClass: 'dark-modal', size: 'lg', centered: true });
  }

  ngOnInit() {
  }

}

This is my photos.component.html file:

<div>
  <div class="col-lg-4 col-sm-6 mb-3">
    <a><img (click)="openDarkModal(content)" id="photo-one" class="img-fluid z-depth-4 relative waves-light" src="#" alt="Image" data-toggle="content" data-target="#content"></a>
  </div>
</div>

<!-- Dark Modal -->
<ng-template #content let-modal id="ng-modal">
  <div class="modal-header dark-modal">
    <img (click)="modal.dismiss('Cross click')" id="modal-image" class="embed-responsive-item img-fluid" src="#" alt="Image" allowfullscreen>
  </div>
    <div class="justify-content-center flex-column flex-md-row list-inline">
      <ul class="list-inline flex-center text-align-center text-decoration-none" id="modal-buttons-list">
        <li><a style="color: white;" href="#"><button mdbBtn type="button" size="sm" class="waves-light" color="indigo" mdbWavesEffect><i class="fab fa-facebook-f"></i></button></a></li>
        <li><a style="color: white;" href="#"><button mdbBtn type="button" size="sm" class="waves-light" color="cyan" mdbWavesEffect><i class="fab fa-twitter"></i></button></a></li>
        <li><a style="color: white;" href="#"><button mdbBtn type="button" size="sm" class="waves-light btn btn-blue-grey" mdbWavesEffect><i class="fas fa-envelope"></i></button></a></li>
      </ul>
    </div>
</ng-template>

and this is where I am with the photos.component.spec.ts file:

import { async, ComponentFixture, TestBed } from '@angular/core/testing';
import { PhotosComponent } from './photos.component';
import { NO_ERRORS_SCHEMA } from '@angular/core';

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

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [ PhotosComponent ],
      schemas: [NO_ERRORS_SCHEMA]
    })
    .compileComponents();
  }));

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

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

  it('should render the first photo', () => {
    const compiled = fixture.debugElement.nativeElement;
    expect(compiled.querySelector('#photo-one')).toBeTruthy();
  });
});

I need the test cases for the elements inside the Dark Modal and the test for the openDarkModal . Except for the code, a reference in Angular 7 testing for beginners would be appreciated.

Answer 1

Let me help you with this one. Lets say you have

app.component.html

<div id="title">
    {{title}}
</div>
<ng-template #content
             let-modal
             id="ng-modal">
  <div class="modal-header dark-modal">
    Header
  </div>
  <div class="justify-content-center flex-column flex-md-row list-inline">
    Body
  </div>
</ng-template>

app.component.ts

import { Component, ViewChild, TemplateRef } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  title = 'AngularProj';
  @ViewChild('content') modalRef: TemplateRef<any>;
}

You need to write spec file with slightly different way:

app.component.spec.ts

import { TestBed, async, ComponentFixture } from '@angular/core/testing';
import { AppComponent } from './app.component';
import { ViewChild, Component, OnInit, AfterContentInit, TemplateRef } from '@angular/core';
import { By } from '@angular/platform-browser';

@Component({
  template: `
    <ng-container *ngTemplateOutlet="modal"> </ng-container>
    <app-root></app-root>
  `,
})
class WrapperComponent implements AfterContentInit {
  @ViewChild(AppComponent) appComponentRef: AppComponent;
  modal: TemplateRef<any>;
  ngAfterContentInit() {
    this.modal = this.appComponentRef.modalRef;
  }
}

describe('AppComponent', () => {
  let app: AppComponent;
  let fixture: ComponentFixture<WrapperComponent>;
  beforeEach(async(() => {
    TestBed.configureTestingModule({
      declarations: [WrapperComponent, AppComponent],
    }).compileComponents();
  }));
  beforeEach(() => {
    fixture = TestBed.createComponent(WrapperComponent);
    const wrapperComponent = fixture.debugElement.componentInstance;
    app = wrapperComponent.appComponentRef;
    fixture.detectChanges();
  });
  it('should create the app', async(() => {
    expect(app).toBeDefined();
  }));
  it('should have title in HtmL ', () => {
    const titleText = (fixture.debugElement.nativeElement.querySelector('#title').innerText);
    expect(titleText).toBe('AngularProj');
  });
  it('should have Header in HtmL ', () => {
    const headerText = (fixture.debugElement.queryAll(By.css('.modal-header.dark-modal'))[0].nativeElement.innerText);
    expect(headerText).toBe('Header');
  });
});

---

1. As you can see, I wrapped the app-root with a sample testing component ( WrapperComponent ).
2. Since, app-root has ng-template , so it won't render on it's own. This creates a tricky situation as we need to render this part of the app.component .
3. Expose ng-template by creating @ViewChild('content') modalRef: TemplateRef<any>; and then using it to render inside WrapperComponent .

I know it seems like a hack but over all the articles I went through, that's how we can achieve this.

---

For testing something like:

openDarkModal(content) {
    this.modalService.open(content, { windowClass: 'dark-modal', size: 'lg', centered: true });
 }

you can use spy , but before that make modalService public so that it can be spied upon:

constructor(public modalService: NgbModal) { }

You can also use jasmine.createSpyObj and keep the service private .

and then in spec :

   import { NgbModalModule } from '@ng-bootstrap/ng-bootstrap';

   TestBed.configureTestingModule({ 
      imports: [NgbModalModule], 
      declarations: [PhotosComponent, /*WrapperComponent*/], 
      schemas: [NO_ERRORS_SCHEMA], 
    })

// and in it block
  it('should call modal Service open function when clicked ', async(() => {
    spyOn(component.modalService,'open').and.callThrough();
    const openModalEle= fixture.debugElement.nativeElement.querySelector('#photo-one'));
     openModalEle.click();
     expect(component.modalService.open).toHaveBeenCalled();    
  }));

Update:

with Angular 11, there are few changes which you will require:

@Component({
  template: `
    <div>
      <ng-container *ngTemplateOutlet="modal"> </ng-container>
    </div>
    <app-root> </app-root> 
  `,
})
class WrapperComponent implements AfterViewInit {
  @ViewChild(AppComponent) appComponentRef: AppComponent;
  modal: TemplateRef<any>;
  constructor(private cdr: ChangeDetectorRef) {}
  ngAfterViewInit() {
    this.modal = this.appComponentRef.modalRef;
    this.cdr.detectChanges();
  }
}
describe('AppComponent', () => {
  let fixture: ComponentFixture<WrapperComponent>;
  let wrapperComponent: WrapperComponent;

  beforeEach(
    waitForAsync(() => {
      TestBed.configureTestingModule({
        declarations: [WrapperComponent, AppComponent],
        imports: [ModalModule.forRoot()],
      }).compileComponents();
    })
  );
  beforeEach(() => {
    fixture = TestBed.createComponent(WrapperComponent);
    wrapperComponent = fixture.debugElement.componentInstance;
    fixture.detectChanges();
  });
  it('should create the app', () => {
    expect(wrapperComponent).toBeDefined();
    expect(wrapperComponent.appComponentRef).toBeDefined();
  });
});