大家好，我是nodejs的初学者。我想在我的代码中测试一些基本的功能。我使用JEST测试框架。在命令提示符中，我使用了npm测试我无法测试我的代码，它显示**npm错误！测试失败。**有人能解决这个问题吗？提前感谢...

lib.test.js:

const lib=require('../lib.js');


describe('absolute',()=>{

    it('It should return positive number if given number is positive',()=>{
        const result=lib.absolute(1);
        expect(result).toBe(1);
    });
    
    it('It should return positive number if given number is negative',()=>{
        const result=lib.absolute(-1);
        expect(result).toBe(1);
    })
    
    it('It should return zero if given number is zero',()=>{
        const result=lib.absolute(0);
        expect(result).toBe(1);
    });

});



lib.js:

// Testing numbers 
module.exports.absolute = function(number) {
  if (number > 0) return number; 
  if (number < 0) return -number; 
  return 0; 
}


package.json:

{
  "name": "testing-demo",
  "version": "1.0.0",
  "description": "",
  "main": "db.js",
  "directories": {
    "test": "tests"
  },
  "dependencies": {},
  "devDependencies": {
    "jest": "^22.2.2"
  },
  "scripts": {
    "test": "jest"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}