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angularkarma-jasmineangular-test

Error: clientWidth is not declared configurable in http://localhost:9877node_modules/jasmine-core/lib/jasmine-core/jasmine.js (line 4410)

I am trying to mock ElementRef properties while unit testing my angular component and it give me the below error

Error: clientWidth is not declared configurable in http://localhost:9877node_modules/jasmine-core/lib/jasmine-core/jasmine.js (line 4410)

I am getting the error when try to mock the property of native element of an element as below

const div = fixture.debugElement.query(By.css('.ellipsis-overflow'));
div.triggerEventHandler('mouseover', null);
fixture.detectChanges();
expect(component.tooltip.isOpen()).toBeFalsy();
spyOnProperty(div.nativeElement, 'clientWidth', 'get').and.returnValue(1400);
spyOnProperty(div.nativeElement, 'scrollWidth', 'get').and.returnValue(2400);

spyOnProperty is creating that error.

Solution

  • clientWidth and scrollWidth are readonly properties of javascript and Its not possible to set value using SpyOn. So you need to use other way by calling other part of the application to set these kind of read only properties.