message: export renderFile() and renderSource() functions
diff: const sass = require('node-sass')
  const {join} = require('path')
  -module.exports = function renderSass(data) {
  - const result = sass.renderSync({
  - data,
  +const defaultOptions = {
  outputStyle: 'compressed',
  includePaths: [join(__dirname, '../node_modules')]
  - })
  +}
  +
  +function renderSync(options) {
  + const result = sass.renderSync(Object.assign({}, defaultOptions, options))
  return result.css.toString()
  }
  +
  +function renderSource(data, otherOptions = {}) {
  + return renderSync({data, ...otherOptions})
  +}
  +
  +function renderFile(file, otherOptions = {}) {
  + return renderSync({file, ...otherOptions})
  +}
  +
  +module.exports = {
  + renderSync,
  + renderSource,
  + renderFile
  +}
  