TypeError: event.target.getAttribute is not a function in Karma Jasmine

Question

Angular component.ts file has this method that is getting called on blur from input field.

dataCapture(event, fieldValue) {
 if (event.target.value !== fieldValue) {
        const controlNameForValidation = event.target.getAttribute('formControlName');
        const altValue = event.target.alt; // event.target.alt;
        const labelNameForAction = event.target.getAttribute('aria-label');
...
}

The input field is as:

<input (blur)="dataCapture($event, initialData.firstName)" aria-label="firstName" type="text" id="firstName" name="firstName" />

And I am trying to write unit test for the above method as follow but even after trying different mock values, getting

TypeError: event.target.getAttribute is not a function

unit test code :

it('should test dataCapture', () => {
 component.initialData = initialData;
 fixture.detectChanges();
 const mockEvent: Event = {
    target: {
      value: 'tes',
      type:'text', id:'firstNameEmp', name:'firstName',
      'aria-Label': 'sectionOne.firstName',
       formControlName: 'firstName'
     },
    stopPropagation: ( ( e: any ) => { /**/ }) as any,
    preventDefault: ( ( e: any ) => { /**/ }) as any,
   } as any as Event;
 component.dataCapture(mockEvent, initialData.firstName);
 expect(component).toBeTruthy(); //expect doesn't matter this time
}

Also tried many other mocking methods, but end result is always same.

Can someone point the right way of mocking to resolve event.target.getAttribute issue!!

Thanks