问如何对以特定格式返回的日期进行单元测试

EN

module.exports = { 
   convertDate
};
function convertDate (date) {
  console.log(date);
    let  date1 = new Date(date);
    console.log(date1);
    let formattedDate = date1.toLocaleDateString('en-GB', {
    day: 'numeric', month: 'short', year: 'numeric'
    }).replace(/ /g, '-');
    console.log( formattedDate);
    return formattedDate;
}    

const expect = require('chai').expect;
const filejs = require('./file.js');

     it.only('should return the date in 25-Feb-2020 format when I pass date in 2020-02-25' ,function () {
       let fdate = filejs.convertDate("2020-02-25");
       expect(fdate).to.equal('25-Feb-2020');

     })