jest preprocessor script for babel 5.x.x

jest-babel.js

// jest-babel.js
//
// usage (package.json):
//  "jest": {
//     "scriptPreprocessor": "jest-babel.js"
//  }
//

var path = require('path');
var babel = require('babel-core');

var hostPackagePath = path.resolve(require('process').cwd(), 'package.json');
var hostPackageInfo = require(hostPackagePath);
var config = {
    stage: 0,
    retainLines: true,
    auxiliaryCommentBefore: 'istanbul ignore next',
};

var configOverrides = hostPackageInfo['jest-babel'] || {};

Object.keys(configOverrides).forEach(function(key) {
    config[key] = configOverrides[key];
});

function process(src, filename) {
    if (!babel.canCompile(filename, config.extensions)) {
        return src;
    }

    config.filename = filename;

    return babel.transform(src, config).code;
}

module.exports = {
    process: process
};