packages/zent/scripts/update-jest-module-mapper.js
function createMapper() {
  var packagesDir = path.resolve(__dirname, '../src');
  var packages = fs.readdirSync(packagesDir);

  return packages
    .filter(p => fs.statSync(path.join(packagesDir, p)).isDirectory())
    .reduce((alias, p) => {
      alias[`^${p}$`] = `<rootDir>/src/${p}`;
      alias[`^${p}/(.+)$`] = `<rootDir>/src/${p}/$1`;
      return alias;
    }, {});
}
function createMapper() {
  var packagesDir = path.resolve(__dirname, '../src');
  var packages = fs.readdirSync(packagesDir);

  return packages
    .filter(p => fs.statSync(path.join(packagesDir, p)).isDirectory())
    .reduce((alias, p) => {
      alias[`^${p}$`] = `<rootDir>/src/${p}`;
      alias[`^${p}/(.+)$`] = `<rootDir>/src/${p}/$1`;
      return alias;
    }, {});
}
为src目录下的所有子目录创建alias