Add validation unit test for semantically equal DaemonSet template updates

pkg/apis/extensions/validation/validation_test.go

@@ -444,6 +444,15 @@ func TestValidateDaemonSetUpdate(t *testing.T) {
 			Spec: validPodSpecAbc,
 		},
 	}
+	validPodTemplateAbcSemanticallyEqual := api.PodTemplate{
+		Template: api.PodTemplateSpec{
+			ObjectMeta: metav1.ObjectMeta{
+				Labels: validSelector,
+			},
+			Spec: validPodSpecAbc,
+		},
+	}
+	validPodTemplateAbcSemanticallyEqual.Template.Spec.ImagePullSecrets = []api.LocalObjectReference{}
 	validPodTemplateNodeSelector := api.PodTemplate{
 		Template: api.PodTemplateSpec{
 			ObjectMeta: metav1.ObjectMeta{
@@ -618,6 +627,33 @@ func TestValidateDaemonSetUpdate(t *testing.T) {
 				},
 			},
 		},
+		"unchanged templateGeneration upon semantically equal template update": {
+			old: extensions.DaemonSet{
+				ObjectMeta: metav1.ObjectMeta{Name: "abc", Namespace: metav1.NamespaceDefault},
+				Spec: extensions.DaemonSetSpec{
+					Selector:           &metav1.LabelSelector{MatchLabels: validSelector},
+					TemplateGeneration: 4,
+					Template:           validPodTemplateAbc.Template,
+					UpdateStrategy: extensions.DaemonSetUpdateStrategy{
+						Type: extensions.OnDeleteDaemonSetStrategyType,
+					},
+				},
+			},
+			update: extensions.DaemonSet{
+				ObjectMeta: metav1.ObjectMeta{Name: "abc", Namespace: metav1.NamespaceDefault},
+				Spec: extensions.DaemonSetSpec{
+					Selector:           &metav1.LabelSelector{MatchLabels: validSelector},
+					TemplateGeneration: 4,
+					Template:           validPodTemplateAbcSemanticallyEqual.Template,
+					UpdateStrategy: extensions.DaemonSetUpdateStrategy{
+						Type: extensions.RollingUpdateDaemonSetStrategyType,
+						RollingUpdate: &extensions.RollingUpdateDaemonSet{
+							MaxUnavailable: intstr.FromInt(1),
+						},
+					},
+				},
+			},
+		},
 	}
 	for testName, successCase := range successCases {
 		// ResourceVersion is required for updates.