text: const Benchmark = require('benchmark');
  const postcss = require('postcss');
  const imageSet = require('./');
  
  
  const suite = new Benchmark.Suite;
  
  const input =
      `a{  
          background-image: image-set(  
              url(img/test.png) 1x,   
              url(img/test-2x.png) 2x,   
              url(my-img-print.png) 600dpi   
          );  
      }`;
  
  suite
      .add('Process CSS', () => {
          postcss(imageSet).process(input).css;
      })
      .on('cycle', event => {
          console.log(String(event.target));
      })
      .run({ 'async': true });