How to use the @inkline/inkline/src/helpers/addClass.addClass function in @inkline/inkline

it('should add multiple classes', () => {
                const spy = jest.spyOn(element.classList, 'add');

                addClass(element, 'class1 class2');

                expect(spy).toHaveBeenCalledTimes(2);
                expect(spy).toHaveBeenCalledWith('class1');
                expect(spy).toHaveBeenCalledWith('class2');
            });
        });

it('should not add class if class already exists', () => {
                element.className = 'test';

                addClass(element, 'test');

                expect(element.className).toEqual('test');
            });

it('should add a class', () => {
                const spy = jest.spyOn(element.classList, 'add');

                addClass(element, 'class');

                expect(spy).toHaveBeenCalled();
                expect(spy).toHaveBeenCalledWith('class');
            });

it('should not add any class if classes not provided', () => {
                addClass(element, '');

                expect(element.className).toEqual('');
            });

it('should return if element not provided', () => {
            expect(addClass(undefined, undefined)).toEqual(undefined);
        });