tests: Fixes variable expansion false positive test

Some of the tests are negative test cases which are supposed to ensure that those
invalid usecases are handled properly.

However, some of the tests are false positives, they can pass due to various reasons.
One such example is: "should fail substituting values in a volume subpath with absolute path".
This test can pass if:

- the Pod cannot start due to various reasons (e.g.: the container image cannot be pulled or does
  not exist).
- the Pod ran to completion, even though the container was not supposed to start in the first place.

test/e2e/common/expansion.go

@@ -367,8 +367,8 @@ func testPodFailSubpath(f *framework.Framework, pod *v1.Pod) {
 		e2epod.DeletePodWithWait(f.ClientSet, pod)
 	}()
 
-	err := e2epod.WaitTimeoutForPodRunningInNamespace(f.ClientSet, pod.Name, pod.Namespace, framework.PodStartShortTimeout)
-	framework.ExpectError(err, "while waiting for pod to be running")
+	err := e2epod.WaitForPodContainerToFail(f.ClientSet, pod.Namespace, pod.Name, 0, "CreateContainerConfigError", framework.PodStartShortTimeout)
+	framework.ExpectNoError(err, "while waiting for the pod container to fail")
 }
 
 func newPod(command []string, envVars []v1.EnvVar, mounts []v1.VolumeMount, volumes []v1.Volume) *v1.Pod {

test/e2e/framework/pod/resource.go

@@ -298,6 +298,29 @@ func podsRunning(c clientset.Interface, pods *v1.PodList) []error {
 	return e
 }
 
+func podContainerFailed(c clientset.Interface, namespace, podName string, containerIndex int, reason string) wait.ConditionFunc {
+	return func() (bool, error) {
+		pod, err := c.CoreV1().Pods(namespace).Get(context.TODO(), podName, metav1.GetOptions{})
+		if err != nil {
+			return false, err
+		}
+		switch pod.Status.Phase {
+		case v1.PodPending:
+			if len(pod.Status.ContainerStatuses) == 0 {
+				return false, nil
+			}
+			containerStatus := pod.Status.ContainerStatuses[containerIndex]
+			if containerStatus.State.Waiting != nil && containerStatus.State.Waiting.Reason == reason {
+				return true, nil
+			}
+			return false, nil
+		case v1.PodFailed, v1.PodRunning, v1.PodSucceeded:
+			return false, fmt.Errorf("pod was expected to be pending, but it is in the state: %s", pod.Status.Phase)
+		}
+		return false, nil
+	}
+}
+
 // LogPodStates logs basic info of provided pods for debugging.
 func LogPodStates(pods []v1.Pod) {
 	// Find maximum widths for pod, node, and phase strings for column printing.

test/e2e/framework/pod/wait.go

@@ -537,3 +537,10 @@ func WaitForNRestartablePods(ps *testutils.PodStore, expect int, timeout time.Du
 	}
 	return podNames, nil
 }
+
+// WaitForPodContainerToFail waits for the given Pod container to fail with the given reason, specifically due to
+// invalid container configuration. In this case, the container will remain in a waiting state with a specific
+// reason set, which should match the given reason.
+func WaitForPodContainerToFail(c clientset.Interface, namespace, podName string, containerIndex int, reason string, timeout time.Duration) error {
+	return wait.PollImmediate(poll, timeout, podContainerFailed(c, namespace, podName, containerIndex, reason))
+}