OnlyAllowNodeZones tests that GetAllCurrentZones returns only zones with Nodes.

Check that the pods using statically created PVs get scheduled to the same zone that the PV is in.

Check that the pods comprising a replication controller get spread evenly across available zones.

Check that the pods comprising a service get spread evenly across available zones.

WaitForSchedulerAfterAction performs the provided action and then waits for scheduler to act on the given pod.