1. A method comprising: receiving, by a network device, a first network policy and a second network policy, where the second network policy includes a modification to the first network policy; receiving, by the network device, network traffic; processing, by the network device, the network traffic according to the first network policy; processing, by the network device, the network traffic according to the second network policy; based on processing the network traffic according to the second network policy, generating, by the network device, a result that includes information that indicates an effect of the modification to the first network policy on handling, by the network device, of the network traffic; based on processing the network traffic according to the first network policy and without applying the second network policy, sending, by the network device, the network traffic to a destination device; storing, by the network device, the result; and transmitting, by the network device, the result to another network device.