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✨ introduce LabelChangedPredicate to trigger event on label change (kubernetes-sigs#1315)
* introduce LabelChangedPredicate to trigger event on label change Signed-off-by: Bruce Ma <[email protected]> * disable duplication linter on predicate tests Signed-off-by: Bruce Ma <[email protected]>
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‎pkg/predicate/predicate.go‎

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Original file line numberDiff line numberDiff line change
@@ -200,6 +200,36 @@ func (AnnotationChangedPredicate) Update(e event.UpdateEvent) bool {
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return !reflect.DeepEqual(e.ObjectNew.GetAnnotations(), e.ObjectOld.GetAnnotations())
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}
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// LabelChangedPredicate implements a default update predicate function on label change.
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//
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// This predicate will skip update events that have no change in the object's label.
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// It is intended to be used in conjunction with the GenerationChangedPredicate, as in the following example:
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//
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// Controller.Watch(
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// &source.Kind{Type: v1.MyCustomKind},
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// &handler.EnqueueRequestForObject{},
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// predicate.Or(predicate.GenerationChangedPredicate{}, predicate.LabelChangedPredicate{}))
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//
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// This will be helpful when object's labels is carrying some extra specification information beyond object's spec,
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// and the controller will be triggered if any valid spec change (not only in spec, but also in labels) happens.
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type LabelChangedPredicate struct {
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Funcs
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}
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// Update implements default UpdateEvent filter for checking label change
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func (LabelChangedPredicate) Update(e event.UpdateEvent) bool {
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if e.ObjectOld == nil {
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log.Error(nil, "Update event has no old object to update", "event", e)
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return false
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}
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if e.ObjectNew == nil {
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log.Error(nil, "Update event has no new object for update", "event", e)
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return false
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}
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return !reflect.DeepEqual(e.ObjectNew.GetLabels(), e.ObjectOld.GetLabels())
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}
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// And returns a composite predicate that implements a logical AND of the predicates passed to it.
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func And(predicates ...Predicate) Predicate {
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return and{predicates}

‎pkg/predicate/predicate_test.go‎

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Original file line numberDiff line numberDiff line change
@@ -414,6 +414,9 @@ var _ = Describe("Predicate", func() {
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})
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// AnnotationChangedPredicate has almost identical test cases as LabelChangedPredicates,
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// so the duplication linter should be muted on both two test suites.
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// nolint:dupl
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Describe("When checking an AnnotationChangedPredicate", func() {
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instance := predicate.AnnotationChangedPredicate{}
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Context("Where the old object is missing", func() {
@@ -610,6 +613,205 @@ var _ = Describe("Predicate", func() {
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})
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})
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// LabelChangedPredicates has almost identical test cases as AnnotationChangedPredicates,
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// so the duplication linter should be muted on both two test suites.
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// nolint:dupl
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Describe("When checking a LabelChangedPredicate", func() {
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instance := predicate.LabelChangedPredicate{}
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Context("Where the old object is missing", func() {
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It("should return false", func() {
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new := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: "baz",
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Namespace: "biz",
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Labels: map[string]string{
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"foo": "bar",
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},
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}}
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evt := event.UpdateEvent{
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ObjectNew: new,
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}
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Expect(instance.Create(event.CreateEvent{})).To(BeTrue())
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Expect(instance.Delete(event.DeleteEvent{})).To(BeTrue())
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Expect(instance.Generic(event.GenericEvent{})).To(BeTrue())
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Expect(instance.Update(evt)).To(BeFalse())
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})
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})
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Context("Where the new object is missing", func() {
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It("should return false", func() {
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old := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: "baz",
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Namespace: "biz",
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Labels: map[string]string{
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"foo": "bar",
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},
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}}
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evt := event.UpdateEvent{
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ObjectOld: old,
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}
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Expect(instance.Create(event.CreateEvent{})).To(BeTrue())
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Expect(instance.Delete(event.DeleteEvent{})).To(BeTrue())
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Expect(instance.Generic(event.GenericEvent{})).To(BeTrue())
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Expect(instance.Update(evt)).To(BeFalse())
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})
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})
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Context("Where the labels are empty", func() {
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It("should return false", func() {
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new := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: "baz",
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Namespace: "biz",
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}}
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old := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: "baz",
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Namespace: "biz",
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}}
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evt := event.UpdateEvent{
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ObjectOld: old,
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ObjectNew: new,
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}
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Expect(instance.Create(event.CreateEvent{})).To(BeTrue())
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Expect(instance.Delete(event.DeleteEvent{})).To(BeTrue())
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Expect(instance.Generic(event.GenericEvent{})).To(BeTrue())
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Expect(instance.Update(evt)).To(BeFalse())
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})
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})
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Context("Where the labels haven't changed", func() {
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It("should return false", func() {
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new := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: "baz",
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Namespace: "biz",
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Labels: map[string]string{
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"foo": "bar",
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},
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}}
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old := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: "baz",
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Namespace: "biz",
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Labels: map[string]string{
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"foo": "bar",
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},
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}}
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evt := event.UpdateEvent{
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ObjectOld: old,
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ObjectNew: new,
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}
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Expect(instance.Create(event.CreateEvent{})).To(BeTrue())
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Expect(instance.Delete(event.DeleteEvent{})).To(BeTrue())
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Expect(instance.Generic(event.GenericEvent{})).To(BeTrue())
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Expect(instance.Update(evt)).To(BeFalse())
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})
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})
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Context("Where a label value has changed", func() {
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It("should return true", func() {
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new := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: "baz",
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Namespace: "biz",
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Labels: map[string]string{
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"foo": "bar",
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},
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}}
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old := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: "baz",
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Namespace: "biz",
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Labels: map[string]string{
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"foo": "bee",
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},
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}}
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evt := event.UpdateEvent{
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ObjectOld: old,
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ObjectNew: new,
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}
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Expect(instance.Create(event.CreateEvent{})).To(BeTrue())
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Expect(instance.Delete(event.DeleteEvent{})).To(BeTrue())
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Expect(instance.Generic(event.GenericEvent{})).To(BeTrue())
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Expect(instance.Update(evt)).To(BeTrue())
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})
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})
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Context("Where a label has been added", func() {
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It("should return true", func() {
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new := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: "baz",
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Namespace: "biz",
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Labels: map[string]string{
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"foo": "bar",
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},
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}}
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old := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: "baz",
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Namespace: "biz",
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Labels: map[string]string{
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"foo": "bar",
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"faa": "bor",
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},
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}}
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evt := event.UpdateEvent{
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ObjectOld: old,
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ObjectNew: new,
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}
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Expect(instance.Create(event.CreateEvent{})).To(BeTrue())
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Expect(instance.Delete(event.DeleteEvent{})).To(BeTrue())
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Expect(instance.Generic(event.GenericEvent{})).To(BeTrue())
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Expect(instance.Update(evt)).To(BeTrue())
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})
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})
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Context("Where a label has been removed", func() {
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It("should return true", func() {
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new := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: "baz",
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Namespace: "biz",
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Labels: map[string]string{
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"foo": "bar",
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"faa": "bor",
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},
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}}
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old := &corev1.Pod{
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ObjectMeta: metav1.ObjectMeta{
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Name: "baz",
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Namespace: "biz",
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Labels: map[string]string{
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"foo": "bar",
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},
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}}
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evt := event.UpdateEvent{
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ObjectOld: old,
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ObjectNew: new,
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}
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Expect(instance.Create(event.CreateEvent{})).To(BeTrue())
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Expect(instance.Delete(event.DeleteEvent{})).To(BeTrue())
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Expect(instance.Generic(event.GenericEvent{})).To(BeTrue())
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Expect(instance.Update(evt)).To(BeTrue())
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})
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})
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})
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Context("With a boolean predicate", func() {
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funcs := func(pass bool) predicate.Funcs {
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return predicate.Funcs{

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