Cook pasta according to package directions.
Meanwhile, in a large bowl, combine the chicken, pineapple, celery, onions, grapes and cranberries.
Drain pasta and rinse in cold water; stir into chicken mixture.
In a small bowl, whisk the ranch dressing and mayonnaise. Pour over salad and toss to coat. Cover and refrigerator for at least 1 hour.
Just before serving, stir in cashews.