# jscoverage 必须指定encoding参数 - fengmk2

# jscoverage 必须指定encoding参数

由于代码越来越多，在进行代码覆盖测试的时候，经常出现jscoverage后的代码跑的测试不正确。
在排除各种干扰后发现，jscoverage对非ascii字符串转换不正确，导致test cases失败了。

## 重现问题

例如代码 `./foo/index.js`

```
exports.getName = function getName() {
  return '你好';
};
```

进行转换

```
$ jscoverage foo foo_cov
```

得到

```
/* automatically generated by JSCoverage - do not edit */
if (typeof _$jscoverage === 'undefined') _$jscoverage = {};
if (! _$jscoverage['index.js']) {
  _$jscoverage['index.js'] = [];
  _$jscoverage['index.js'][2] = 0;
  _$jscoverage['index.js'][3] = 0;
}
_$jscoverage['index.js'][2]++;
exports.getName = (function getName() {
  _$jscoverage['index.js'][3]++;
  return "\u00e4\u00bd\u00a0\u00e5\u00a5\u00bd";
});
_$jscoverage['index.js'].source = ["","exports.getName = function getName() {","  return '你好';","};"];
```

明显看到 `'你好'` 被转换的编码出现错误了 `"\u00e4\u00bd\u00a0\u00e5\u00a5\u00bd"`

于是猜测 `jscoverage` 估计有指定编码的参数

```
$ jscoverage -h
Usage: jscoverage SOURCE-DIRECTORY DESTINATION-DIRECTORY
Instrument JavaScript with code coverage information.

Options:
      --encoding=ENCODING   assume .js files use the given character encoding
      --exclude=PATH        do not copy PATH
      --js-version=VERSION  use the specified JavaScript version
      --no-highlight        do not perform syntax highlighting
      --no-instrument=PATH  copy but do not instrument PATH
  -v, --verbose             explain what is being done
  -h, --help                display this help and exit
  -V, --version             display version information and exit
```

果然不出所料, `encoding` 能指定文件的编码

于是重现转换

```
$ jscoverage --encoding=utf-8 foo foo_cov_utf8
```

得到的文件编码终于正确了

```
/* automatically generated by JSCoverage - do not edit */
if (typeof _$jscoverage === 'undefined') _$jscoverage = {};
if (! _$jscoverage['index.js']) {
  _$jscoverage['index.js'] = [];
  _$jscoverage['index.js'][2] = 0;
  _$jscoverage['index.js'][3] = 0;
}
_$jscoverage['index.js'][2]++;
exports.getName = (function getName() {
  _$jscoverage['index.js'][3]++;
  return "\u4f60\u597d";
});
_$jscoverage['index.js'].source = ["","exports.getName = function getName() {","  return '你好';","};"];
```

可以看到 `'你好'` 被正确转换成 `"\u4f60\u597d"`

## 验证脚本

`jscoverage-must-set-encoding.js`:

```
var foo = require('./foo');
var foo_cov = require('./foo_cov');
var foo_cov_utf8 = require('./foo_cov_utf8');

console.log('foo', foo.getName(), foo.getName() === '你好');
console.log('foo_cov', foo_cov.getName(), foo_cov.getName() === '你好');
console.log('foo_cov_utf8', foo_cov_utf8.getName(), foo_cov_utf8.getName() === '你好');
```

输出:

```
foo 你好 true
foo_cov 你好 false
foo_cov_utf8 你好 true
```

## 有爱

推荐阅读: [Setting up Mocha & JSCoverage](http://www.seejohncode.com/2012/03/13/setting-up-mocha-jscoverage/)

^\_^ 希望本文对你有用.