Warhurst has spent the past few days training with Town in a bid to win a contract.
Law has been impressed by what he's seen in training and offered the former England cap non-contract terms until the end of the season, with a review in the pre-season.
The 34-year-old joins Alan Fettis and John Thorrington as new boys at the club and will go straight in the sixteen for tomorrow's crucial game with Bournemouth.