Merge pull request #27900 from derekwaynecarr/test_defaults_qos

Automatic merge from submit-queue

Add additional testing scenarios for compute resource requests=0

I was asked about the qos tier of a pod that specified 

`--requests=cpu=0,memory=0 --limits=cpu=100m,memory=1Gi`

and in just investigating current behavior, realized we should have an explicit test case to ensure that 0 values are preserved in defaulting passes, and that this is still a burstable pod (but the lowest for that tier as it related to eviction)

/cc @vishh

pkg/kubelet/qos/qos_test.go

@@ -123,6 +123,12 @@ func TestGetPodQOS(t *testing.T) {
 			}),
 			expected: Burstable,
 		},
+		{
+			pod: newPod("burstable", []api.Container{
+				newContainer("burstable", getResourceList("0", "0"), getResourceList("100m", "200Mi")),
+			}),
+			expected: Burstable,
+		},
 	}
 	for _, testCase := range testCases {
 		if actual := GetPodQOS(testCase.pod); testCase.expected != actual {