Unit test Angular mock HTML Document-CodePudding

I have one method in my component.ts and i would like to know how can i test the method below:

print(i) {
    (document.getElementById("iframe0) as any).contentWindow.print();
}

I don't know how to mock html document with one iframe to call this method.

Anyone knows....

i would like to know how to mock document html to create for example one instance and check if my method is printing html document.

CodePudding user response：

Is there a typo in the code? Missing " after iframe0, and is the 0 intentional or is that the key that was hit by mistake?

It looks to me as it should be

print(i) {
    (document.getElementById("iframe0") as any).contentWindow.print();
}

CodePudding user response：

To test the print() method in your Angular component, you can use the TestBed class from the @angular/core/testing module to create a mock environment for your test.

Here's an example of how you can use the TestBed class to test the print() method:

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

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

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

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

  it('should print the document', () => {
    // Create a mock HTML document with an iframe element
    const doc = document.implementation.createHTMLDocument();
    const iframe = doc.createElement('iframe');
    iframe.id = 'iframe0';
    doc.body.appendChild(iframe);

    // Set the mock document as the current document
    spyOn(component, 'print').and.callThrough();
    (global as any).document = doc;

    // Call the print method
    component.print();

    // Verify that the print method was called
    expect(component.print).toHaveBeenCalled();
  });
});

In this example, we use the createHTMLDocument() method of the Document interface to create a mock HTML document, and then create an iframe element and append it to the document. We then set the mock document as the current document using the global object, and call the print() method.

Finally, we use the toHaveBeenCalled() matcher to verify that the print() method was called.

This is just one example of how you can test the print() method. You may need to adjust the test depending on your specific requirements.