restore event Gone test

staging/src/k8s.io/apiserver/pkg/storage/tests/cacher_test.go

@@ -57,6 +57,11 @@ var (
 	codecs = serializer.NewCodecFactory(scheme)
 )
 
+const (
+	// watchCacheDefaultCapacity syncs watch cache defaultLowerBoundCapacity.
+	watchCacheDefaultCapacity = 100
+)
+
 func init() {
 	metav1.AddToGroupVersion(scheme, metav1.SchemeGroupVersion)
 	utilruntime.Must(example.AddToScheme(scheme))
@@ -101,6 +106,10 @@ func newEtcdTestStorage(t *testing.T, prefix string) (*etcd3testing.EtcdTestServ
 }
 
 func newTestCacher(s storage.Interface, cap int) (*cacherstorage.Cacher, storage.Versioner, error) {
+	return newTestCacherWithClock(s, cap, clock.RealClock{})
+}
+
+func newTestCacherWithClock(s storage.Interface, cap int, clock clock.Clock) (*cacherstorage.Cacher, storage.Versioner, error) {
 	prefix := "pods"
 	v := etcd3.APIObjectVersioner{}
 	config := cacherstorage.Config{
@@ -113,7 +122,7 @@ func newTestCacher(s storage.Interface, cap int) (*cacherstorage.Cacher, storage
 		NewFunc:        func() runtime.Object { return &example.Pod{} },
 		NewListFunc:    func() runtime.Object { return &example.PodList{} },
 		Codec:          codecs.LegacyCodec(examplev1.SchemeGroupVersion),
-		Clock:          clock.RealClock{},
+		Clock:          clock,
 	}
 	cacher, err := cacherstorage.NewCacherFromConfig(config)
 	return cacher, v, err
@@ -396,7 +405,8 @@ func TestWatch(t *testing.T) {
 	// Inject one list error to make sure we test the relist case.
 	etcdStorage = &injectListError{errors: 1, Interface: etcdStorage}
 	defer server.Terminate(t)
-	cacher, _, err := newTestCacher(etcdStorage, 3) // small capacity to trigger "too old version" error
+	fakeClock := clock.NewFakeClock(time.Now())
+	cacher, _, err := newTestCacherWithClock(etcdStorage, watchCacheDefaultCapacity, fakeClock)
 	if err != nil {
 		t.Fatalf("Couldn't create cacher: %v", err)
 	}
@@ -439,15 +449,6 @@ func TestWatch(t *testing.T) {
 	verifyWatchEvent(t, watcher, watch.Added, podFoo)
 	verifyWatchEvent(t, watcher, watch.Modified, podFooPrime)
 
-	// Check whether we get too-old error via the watch channel
-	tooOldWatcher, err := cacher.Watch(context.TODO(), "pods/ns/foo", storage.ListOptions{ResourceVersion: "1", Predicate: storage.Everything})
-	if err != nil {
-		t.Fatalf("Expected no direct error, got %v", err)
-	}
-	defer tooOldWatcher.Stop()
-	// Events happens in eventFreshDuration, cache expand without event "Gone".
-	verifyWatchEvent(t, tooOldWatcher, watch.Added, podFoo)
-
 	initialWatcher, err := cacher.Watch(context.TODO(), "pods/ns/foo", storage.ListOptions{ResourceVersion: fooCreated.ResourceVersion, Predicate: storage.Everything})
 	if err != nil {
 		t.Fatalf("Unexpected error: %v", err)
@@ -468,6 +469,25 @@ func TestWatch(t *testing.T) {
 	_ = updatePod(t, etcdStorage, podFooBis, fooUpdated)
 
 	verifyWatchEvent(t, nowWatcher, watch.Modified, podFooBis)
+
+	// Add watchCacheDefaultCapacity events to make current watch cache full.
+	// Make start and last event duration exceed eventFreshDuration(current 75s) to ensure watch cache won't expand.
+	for i := 0; i < watchCacheDefaultCapacity; i++ {
+		fakeClock.SetTime(time.Now().Add(time.Duration(i) * time.Minute))
+		podFoo := makeTestPod(fmt.Sprintf("foo-%d", i))
+		updatePod(t, etcdStorage, podFoo, nil)
+	}
+
+	// Check whether we get too-old error via the watch channel
+	tooOldWatcher, err := cacher.Watch(context.TODO(), "pods/ns/foo", storage.ListOptions{ResourceVersion: "1", Predicate: storage.Everything})
+	if err != nil {
+		t.Fatalf("Expected no direct error, got %v", err)
+	}
+	defer tooOldWatcher.Stop()
+
+	// Ensure we get a "Gone" error.
+	expectedResourceExpiredError := errors.NewResourceExpired("").ErrStatus
+	verifyWatchEvent(t, tooOldWatcher, watch.Error, &expectedResourceExpiredError)
 }
 
 func TestWatcherTimeout(t *testing.T) {