unit test case for aync.parallel

Can some one help me to figure out how to write/mock unit test in jasmine for below code

async.parallel([
    function (callback) {
        var resp = {};
        var sample = spawn(cmd, ['args']);
        sample.stdout.on('data', function (chunk) {
            resp = chunk;
        });
        sample.stderr.on('data', function (chunk) {
            resp = chunk;

        });
        sample.on('close', function (code) {
            if (code != 0) {
                //console.log('code not zero');
            }
            callback(null, resp);
        })
    }

], function (err, results) {
   console.log(results);
});