No coverage information was collected, exit without writing coverage information es6
解决方法1：
有问题的branch：https://github.com/JakeSidSmith/istanbul-no-coverage
运行成功的branch：https://github.com/JakeSidSmith/istanbul-no-coverage/pull/1
"scripts": {
"start": "http-server . -c-1 -o",
"build": "mkdir -p build/js/ && browserify -t babelify src/js/index.js -o build/js/index.js",
- "test": "istanbul cover node_modules/mocha/bin/_mocha -- --compilers js:babel-core/register --require test-helper.js --harmony --bail --recursive 'src/js/__tests__/**/*.test.js'"
+ "test": "babel-node ./node_modules/istanbul/lib/cli cover node_modules/mocha/bin/_mocha -- --require test-helper.js --bail --recursive 'src/js/__tests__/**/*.test.js'"
},
"author": "",
"license": "ISC",
@@ -20,11 +20,12 @@
"react-dom": "=0.14.2"
},
"devDependencies": {
+ "babel-cli": "^6.2.0",
"babel-core": "=6.2.1",
"chai": "=3.4.1",
"chai-immutable": "=1.5.3",
"http-server": "=0.8.5",
- "istanbul": "=0.4.1",
+ "istanbul": "^1.0.0-alpha",
"jsdom": "=7.1.0",
"mocha": "=2.3.4",
"react-addons-test-utils": "=0.14.2",
测验有效，但是我istanbul版本是最新的"istanbul":"^0.4.5"，而且作者也说这种方法在其他版本里面可能会出现问题。
解决方法2：
使用babel-istanbul in lieu of istanbul
"test:coverage": "babel-node ./node_modules/.bin/babel-istanbul cover ./node_modules/.bin/_mocha ./src/**/__tests__/*.js"
stackoverflow原问题地址
Transformation error; return original code
创建一个.istanbul.yml文件，内容
instrumentation:
root: src
或者在命令行添加 --root /src
在使用了babel-istanbul之后，这个问题不需要.istanbul.yml文件和命令行设置也可以工作了。
更多的讨论
Window is not defined
可以用jsdom-global来fix这个问题，介绍很清晰明了。
jsdom-global will inject document, window and other DOM API into your Node.js environment. Useful for running, in Node.js, tests that are made for browsers.
npm install --save-dev --save-exact jsdom jsdom-global
然后把-r jsdom-global/register加到mocha的command line里面。
最后我在package.json中的设置
"test-cov": "babel-node ./node_modules/.bin/babel-istanbul cover _mocha -- --recursive './frontend/**/*.test.js' -r jsdom-global/register"
运行结果：
25 passing (57ms)
=============================== Coverage summary ===============================
Statements : 81.96% ( 559/682 )
Branches : 88.46% ( 150/169 ), 2 ignored
Functions : 81.43% ( 114/140 )
Lines : 80.67% ( 480/595 )
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