Use `execFile` instead of `exec` about grunt-zopfli

[alrra]

It's because of

options.splitLast ? '--splitlast' : '',

which, when splitLast is undefined, will generate something like

zopfli '-c' '--i25' '--deflate' '' 'tests/fixtures/benchmark.js'

that, when executed, will give you

Invalid filename: 

due to the '' argument.

So, add only "real" options as arguments.

---

Try something like:

var zopfli = function(filePath, options, callback) {      

    var args = [                                                                 
        '-c',                                                                    
        '--i' + options.iterations,                                              
        options.format == 'gzip' ? '--gzip'                                      
            : options.format == 'deflate' ? '--deflate'                          
                : '--zlib',                                                      
        filePath                                                                 
    ];                                                                           

    if ( options.splitLast ) {                                                   
        args.push('--splitlast');                                            
    };                                                                           

    execFile('zopfli', args, function(error, stdout, stderr) {                         
        callback.call(this, error || stderr, stdout);                            
    });                                                                          
};     

[mathiasbynens]

Weird, you’re absolutely correct that this was the issue — thanks! — but test-1 and test-2 were working fine and they had splitLast: false too.

To debug this, I was trying to find a way to get execFile to log the full command before executing it or something (I assumed it wasn’t quoting the arguments but rather escaping special characters as needed), but it seems impossible without using strace / dtruss :(

Anyhow, it’s fixed now. Thanks!