text: import isValidDate from './isValidDate';
  
  describe('isValidDate test.', () => {
    it('invalid date test', () => {
      const date = new Date(NaN);
  
      expect(isValidDate(date)).toBeFalsy();
    });
  
    it('valid date test', () => {
      const date = new Date(2019, 1, 1);
  
      expect(isValidDate(date)).toBeTruthy();
    });
  });
  