javascript 是否可以在 Mocha 测试中使用 ES6 模块？
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Is it possible to use ES6 modules in Mocha tests?
提问by Andrey Bushman
ES6, Windows 10 x64, Node.js 8.6.0, Mocha 3.5.3
ES6、Windows 10 x64、Node.js 8.6.0、Mocha 3.5.3
Is it possible to use ES6 modules in Mocha tests? I have the problems with exportand importkeywords.
是否可以在 Mocha 测试中使用 ES6 模块？我有export和import关键字的问题。
/* eventEmitter.js
*/
/* Event emitter. */
export default class EventEmitter{
constructor(){
const subscriptions = new Map();
Object.defineProperty(this, 'subscriptions', {
enumerable: false,
configurable: false,
get: function(){
return subscriptions;
}
});
}
/* Add the event listener.
* @eventName - the event name.
* @listener - the listener.
*/
addListener(eventName, listener){
if(!eventName || !listener) return false;
else{
if(this.subscriptions.has(eventName)){
const arr = this.subscriptions.get(eventName);
arr.push(listener);
}
else{
const arr = [listener];
this.subscriptions.set(eventName, arr);
}
return true;
}
}
/* Delete the event listener.
* @eventName - the event name.
* @listener - the listener.
*/
deleteListener(eventName, listener){
if(!eventName || !listener) return false;
else{
if(this.subscriptions.has(eventName)){
const arr = this.subscriptions.get(eventName);
let index = arr.indexOf(listener);
if(index >= 0){
arr.splice(index, 1);
return true;
}
else{
return false;
}
}
else{
return false;
}
}
}
/* Emit the event.
* @eventName - the event name.
* @info - the event argument.
*/
emit(eventName, info){
if(!eventName || !this.subscriptions.has(eventName)) {
return false;
}
else{
for(let fn of this.subscriptions.get(eventName)){
if(fn) fn(info);
}
return true;
}
}
}
Mocha test:
摩卡测试：
/* test.js
* Mocha tests.
*/
import EventEmitter from '../../src/js/eventEmitter.js';
const assert = require('assert');
describe('EventEmitter', function() {
describe('#constructor()', function() {
it('should work.', function() {
const em = new EventEmitter();
assert.equal(true, Boolean(em));
});
});
});
I launch the mochadirectly through the PowerShell console. The result:
我mocha直接通过 PowerShell 控制台启动。结果：
采纳答案by Osama Bari
It's possible with Babel and Browserfy https://drublic.de/blog/es6-modules-using-browserify-mocha/
可以使用 Babel 和 Browserfy https://drublic.de/blog/es6-modules-using-browserify-mocha/
回答by JLRishe
Mocha has support for ESMfrom version 7.1.0 onward (release: Feb. 26, 2020).
Mocha从 7.1.0 版本开始支持 ESM（发布：2020 年 2 月 26 日）。
This requires Node 12.11.0 or higher, and is subject to the current restrictions/limitations of using modules in Node:
这需要 Node 12.11.0 或更高版本，并且受当前在 Node 中使用模块的限制/限制：
- Either you must use .mjs file extensions for source files that use ES modules, or you must have
"type": "module"in your package.json - You can't use named imports with CommonJS modules
- 对于使用 ES 模块的源文件，您必须使用 .mjs 文件扩展名，或者您
"type": "module"的 package.json 中必须有 - 你不能在 CommonJS 模块中使用命名导入
And so on.
等等。
Another option is to use the esmpackage, which is not subject to the above limitations:
另一种选择是使用esm包，它不受上述限制：
mocha -r esm
My personal experience as of yet is that trying to take advantage of Mocha's new, inherent ESM support is still a considerable burden, but using the esm package is quite seamless.
到目前为止，我个人的经验是，试图利用 Mocha 新的、固有的 ESM 支持仍然是一个相当大的负担，但使用 esm 包是非常无缝的。
