Testing response from a call back failure.

So I have some code that requires waiting for a call back and testing the response of it.

For some reason the callback never managed to get called. I've stepped through the code with the debugger but the nodeunit process finishes (with unfinished tests) before the callback can actually fire. I have no doubt I am doing something wrong but no idea what.

This is the test code I'm using:

```
exports["Strip - Firmata"] = {
setUp: function(done){
this.board = newBoard();
done();
},
tearDown: function(done) {
Board.purge();
restore(this);
done();
},

stripReady: function(test) {
test.expect(1);

var strip = new pixel.Strip({
data: 6,
length: 8,
board: this.board,
controller: "FIRMATA",
});

strip.on("ready", function() {
console.log("strip ready");
test.ok(true);
test.done();
});
},
}
```

For context: The `stripReady` test needs to test that a particular event is being emitted by the strip object once it's good to go (this is talking to some hardware behind the scenes). Down the line I'll want to test the appropriate error events as well.

When I trace this with the debugger, the strip constructor gets called, the handler gets bound but right at the moment the handler is bound nodeunit then exits.

As such it doesn't get a chance to drop into the ready handler shown above. I can trace to the point where it emits the message on the `Strip` side but that event handler never gets called.

So the question is how do I get nodeunit to hang around long enough to get the response back?

FYI the strip constructor is correct and it working properly with the hardware.

Comienza con la prueba stripReady mostrada y el ciclo de vida de pruebas asíncronas de nodeunit; después, ejecuta la prueba con la configuración de hardware descrita en el issue. Se considera completado cuando se observa el evento ready y su assertion finaliza antes de que nodeunit termine, y el comportamiento es reproducible o está explicado.

Escrito por el modelo de indexación a partir del texto del issue.