javascript - 如何在浏览器中公开外部库以便 Jest 单元测试可以看到它？

Question

我正在编写一个在浏览器中使用的数学库，并使用 Jest 对其运行单元测试(我意识到它更适合 Node)。我已经通过扩展 JS Math 解决了大部分问题，但是为了求平均(均值)和标准差，我正在使用 https://mathjs.org的数学图书馆。这在浏览器中一切正常，但 Jest 无法看到 mathjs 库，我不确定如何修复它。

这是在 Jest (CalRunWebMath.js) 中失败的特定代码部分:

//Extend Math to calculate coefficient of variation:
Math.cv = function(numericArray){
    var std = math.std(numericArray);
    var mean = math.mean(numericArray);
    //this is how I originally did it:
    //return math.std(numericArray)/math.mean(numericArray);
    return std/mean;
}
try {
    module.exports.cv = exports = Math.cv;
}
catch (e) {}

//and this is a snippet of the internal tests that works just fine in the browser, but not in Jest
var data1 = [10.4,20.3,30.2,40.1];
console.log(Math.cv(data1)); //0.5061720808904743

这是驱动它的 HTML:

<script src='js/math.js'></script>
<script src='js/CalRunWebMath.js'></script>

这是 Jest 测试文件:

const crwm = require('./CalRunWebMath.js');
const math = require('./math.js');
const cv = crwm.cv;

test('Calculates coefficient of variation', ()=> {
    var data1 = [10.4,20.3,30.2,40.1];
    expect(cv(data1)).toBe(0.5061720808904743);
});

我收到的错误是:ReferenceError: math is not defined (我从上面的代码片段中省略了其他通过的测试):

 FAIL  ./CalRunWebMath.test.js
  √ Calculates slope of two coordinates (6ms)
  × Calculates coefficient of variation (4ms)
  √ Calculates Y-intercept of two coordinates (1ms)
  √ Calculates the mean of an array of decimals (48ms)

  ● Calculates coefficient of variation

    ReferenceError: math is not defined

      43 | Math.cv = function(numericArray){
      44 |      //console.log(math.std);
    > 45 |      var std = math.std(numericArray);
         |                ^
      46 |      var mean = math.mean(numericArray);
      47 |      //return math.std(numericArray)/math.mean(numericArray);
      48 |      return std/mean;

      at math (js/CalRunWebMath.js:45:12)
      at Object.cv (js/CalRunWebMath.test.js:14:9)

Test Suites: 1 failed, 1 total
Tests:       1 failed, 3 passed, 4 total

如何在浏览器中公开数学模块以便 Jest 可以在测试中看到它？

Answer 1

Node 中的全局命名空间对象可用作 global。

您可以像这样将math 添加到全局命名空间对象:

global.math = require('./math.js');
const { cv } = require('./CalRunWebMath.js');

test('Calculates coefficient of variation', () => {
  var data1 = [10.4, 20.3, 30.2, 40.1];
  expect(cv(data1)).toBe(0.5061720808904743);  // Success!
});