Simplicity Studio® 5 (SSv5) offers a number of tools that can be used to test and debug application functionality, power consumption, and network behavior.
In addition, a number of SDKs provide example applications that can be used for testing, such as:
NodeTest (Zigbee EmberZNet SDK) (See AN1019: Using the NodeTest Application) - Deprecated in Zigbee EmberZNet SDK 188.8.131.52
RAILtest (Proprietary Flex SDK) (see UG409: RAILtest User's Guide)
Finally, Silicon Labs provides a number of other documentation resources related to testing such as: