Add test coverage for stack edge learning.
Add test coverage for stack edge learning.

mwutzke/faucet,wackerly/faucet,mwutzke/faucet,trentindav/faucet,faucetsdn/faucet,shivarammysore/faucet,trungdtbk/faucet,REANNZ/faucet,trentindav/faucet,REANNZ/faucet,anarkiwi/faucet,faucetsdn/faucet,gizmoguy/faucet,shivarammysore/faucet,gizmoguy/faucet,wackerly/faucet,anarkiwi/faucet,trungdtbk/faucet