pngjs/test/test.js

var fs = require('fs'),
    PNG = require('../lib/png').PNG;

fs.readdir(__dirname + '/in/', function(err, files) {
    if (err) throw err;

    files.forEach(function(file) {

        if (!file.match(/.*\.png$/i))
            return;

        var expectedError = false;
        if (file.match(/^x/)) {
            expectedError = true;
        }

        var data = fs.readFileSync(__dirname + '/in/' + file);
        try {
            var png = PNG.sync.read(data);
        } catch (e) {
            if (!expectedError) {
                console.log("Unexpected error parsing.." + file);
                console.log(e);
                console.log(e.stack);
            }
            return;
        }

        if (expectedError) {
            console.log("Error expected, parsed fine ..", file);
        }

        var outpng = new PNG();
        PNG.adjustGamma(png);
        outpng.data = png.data;
        outpng.width = png.width;
        outpng.height = png.height;
        outpng.pack()
          .pipe(fs.createWriteStream(__dirname + '/outsync/' + file));

        fs.createReadStream(__dirname + '/in/' + file)
            .pipe(new PNG())
            .on('error', function(err) {
              if (!expectedError) {
                  console.log("Error reading " + file, err);
              }
            })
            .on('parsed', function() {

                if (expectedError) {
                    console.log("Error expected, parsed fine", file);
                }

                this.adjustGamma();

                this.pack()
                  .pipe(fs.createWriteStream(__dirname + '/out/' + file));

            });

    });
});