1. A system for validating a routing function for a network device, comprising: a network device comprising a run-time policy engine, the run-time policy engine being arranged to implement a routing configuration file, the routing configuration file defining a routing function for network traffic; and a file editor arranged to load the routing configuration file, the file editor comprising an editor policy engine that duplicates a functionality of the run-time policy engine, wherein the routing configuration file comprises at least one validation portion, the validation portion comprising one or more route statements with definitions indicative of expected routing function behavior, wherein the file editor is arranged to parse the routing configuration file by implementing the routing configuration file using the editor policy engine, the editor policy engine being arranged to apply the routing function defined by the routing configuration file to the one or more route statements and to indicate where a result of the routing function does not conform to the definitions indicative of expected routing function behavior.