chai.request attach files array

I'm writing a generic test function with chai.request, here is what I have:

//this is in some function
    var file = fs.readFileSync(__dirname + '/../test/files/' + args.fileName);
    chai.request(server)
            .post('/v2')
            .field('email', args.email)
            .field('subject', args.subject)
            .attach('fileName', file, args.fileName)
            .end((err, res) => {
                //some test conditions

                done();
            });

This works great if there is only 1 file passed, the problem is that sometimes I need to pass in an array of files, but I have no idea how to attach those when I'm not sure of the number of files coming in.

via Mankind1023