WHAT
Once autoscaling is fully implemented, an E2E test in PROW should be used to test that autoscaling is working correctly. 

HOW
Write E2E that enables autoscaling, and checks that HPA CRs are created successfully and that they are in the ready to scale state. Then disable autoscaling and check that the HPA CRs were cleaned up.

This method isn't written in stone, but the idea is that the E2E test should not let autoscaling scale up the pods but should check for a ready to scale state or use some other method to check autoscaling is working without checking that replica counts for deployments have increased. This is because Prow uses custom replica counts for some deployments. Once autoscaling is enabled, it will try to scale up the pod counts after a couple of minutes and could cause the PROW cluster to fail. Checking that autoscaling is working before it can scale up would suffice for this test.

TESTS
E2E test

DONE
Autoscaling E2E test runs and passes in PROW