e2e: addressed reviewers comments

* Check the retunred output is not empty
* Use `GinkgoHelper()`

Signed-off-by: Talor Itzhak <titzhak@redhat.com>

test/e2e/performanceprofile/functests/11_mixedcpus/mixedcpus.go

@@ -246,10 +246,12 @@ var _ = Describe("Mixedcpus", Ordered, func() {
 				cmd := printMixedCPUsEnvCmd()
 				output, err := pods.ExecCommandOnPod(testclient.K8sClient, p, "", cmd)
 				Expect(err).ToNot(HaveOccurred(), "failed to execute command on pod; cmd=%q pod=%q", cmd, client.ObjectKeyFromObject(p).String())
+				Expect(output).ToNot(BeEmpty())
 				isolatedAndShared := strings.Split(string(output), "\r\n")
 				isolatedFromEnv := mustParse(isolatedAndShared[0])
 				Expect(isolatedFromEnv.IsEmpty()).ToNot(BeTrue())
 				sharedFromEnv := mustParse(isolatedAndShared[1])
+				Expect(sharedFromEnv.IsEmpty()).ToNot(BeTrue())
 				Expect(sharedFromEnv.Equals(newShared)).To(BeTrue(), "OPENSHIFT_SHARED_CPUS value not equal to what configure in the performance profile."+
 					"OPENSHIFT_SHARED_CPUS=%s spec.cpu.shared=%s", sharedFromEnv.String(), newShared.String())
 
@@ -394,7 +396,8 @@ func getTestingNamespace() corev1.Namespace {
 }
 
 func mustParse(cpus string) *cpuset.CPUSet {
+	GinkgoHelper()
 	set, err := cpuset.Parse(cpus)
-	ExpectWithOffset(1, err).ToNot(HaveOccurred(), "failed to parse cpuset; cpus=%q", cpus)
+	Expect(err).ToNot(HaveOccurred(), "failed to parse cpuset; cpus=%q", cpus)
 	return &set
 }