Make sure required PVC is created in reconciler test 👶

When I was working on tektoncd#1417 (which added the ability to create PVCs for
the Volume Resource and has since been abandoned) I was surprised to
realize that the reconciler test for the PipelineRun controller doesn't
verify that the PVC has been created. It does make sure its attached and
this is covered by the end to end tests that wouldn't work without it,
but I thought it made sense to test here too since we can.

pkg/reconciler/pipelinerun/pipelinerun_test.go

@@ -278,6 +278,9 @@ func TestReconcile(t *testing.T) {
 	if _, exists := reconciledRun.Status.TaskRuns["test-pipeline-run-success-unit-test-cluster-task-78c5n"]; !exists {
 		t.Errorf("Expected PipelineRun status to include TaskRun status but was %v", reconciledRun.Status.TaskRuns)
 	}
+
+	// A PVC should have been created to deal with output -> input linking
+	ensurePVCCreated(t, clients, expectedTaskRun.GetPipelineRunPVCName(), "foo")
 }
 
 func TestReconcile_InvalidPipelineRuns(t *testing.T) {
@@ -1588,3 +1591,20 @@ func makeExpectedTr(condName, ccName string) *v1alpha1.TaskRun {
 		),
 	)
 }
+
+func ensurePVCCreated(t *testing.T, clients test.Clients, name, namespace string) {
+	t.Helper()
+	_, err := clients.Kube.CoreV1().PersistentVolumeClaims(namespace).Get(name, metav1.GetOptions{})
+	if err != nil {
+		t.Errorf("Expected PVC %s to be created for VolumeResource but did not exist", name)
+	}
+	pvcCreated := false
+	for _, a := range clients.Kube.Actions() {
+		if a.GetVerb() == "create" && a.GetResource().Resource == "persistentvolumeclaims" {
+			pvcCreated = true
+		}
+	}
+	if !pvcCreated {
+		t.Errorf("Expected to see volume resource PVC created but didn't")
+	}
+}