import isUndefined from '../../utils/isUndefined'; describe('isUndefined', () => { it('should return true when it is an undefined value', () => { expect(isUndefined(undefined)).toBeTruthy(); }); it('should return false when it is not an undefined value', () => { expect(isUndefined(null)).toBeFalsy(); expect(isUndefined('')).toBeFalsy(); expect(isUndefined('undefined')).toBeFalsy(); expect(isUndefined(0)).toBeFalsy(); expect(isUndefined([])).toBeFalsy(); expect(isUndefined({})).toBeFalsy(); }); });