Fix Test Flakiness by adding short sleep in TestMetricsRefresh

pkg/epp/backend/metrics/pod_metrics.go

@@ -42,8 +42,9 @@ type podMetrics struct {
 	ds       Datastore
 	interval time.Duration
 
-	once sync.Once // ensure the StartRefreshLoop is only called once.
-	done chan struct{}
+	startOnce sync.Once // ensures the refresh loop goroutine is started only once
+	stopOnce  sync.Once // ensures the done channel is closed only once
+	done      chan struct{}
 
 	logger logr.Logger
 }
@@ -86,7 +87,7 @@ func toInternalPod(pod *corev1.Pod) *backend.Pod {
 // start starts a goroutine exactly once to periodically update metrics. The goroutine will be
 // stopped either when stop() is called, or the given ctx is cancelled.
 func (pm *podMetrics) startRefreshLoop(ctx context.Context) {
-	pm.once.Do(func() {
+	pm.startOnce.Do(func() {
 		go func() {
 			pm.logger.V(logutil.DEFAULT).Info("Starting refresher", "pod", pm.GetPod())
 			ticker := time.NewTicker(pm.interval)
@@ -138,5 +139,7 @@ func (pm *podMetrics) refreshMetrics() error {
 
 func (pm *podMetrics) StopRefreshLoop() {
 	pm.logger.V(logutil.DEFAULT).Info("Stopping refresher", "pod", pm.GetPod())
-	close(pm.done)
+	pm.stopOnce.Do(func() {
+		close(pm.done)
+	})
 }

pkg/epp/backend/metrics/pod_metrics_test.go

@@ -78,6 +78,7 @@ func TestMetricsRefresh(t *testing.T) {
 	// Stop the loop, and simulate metric update again, this time the PodMetrics won't get the
 	// new update.
 	pm.StopRefreshLoop()
+	time.Sleep(pmf.refreshMetricsInterval * 2 /* small buffer for robustness */)
 	pmc.SetRes(map[types.NamespacedName]*MetricsState{namespacedName: updated})
 	// Still expect the same condition (no metrics update).
 	assert.EventuallyWithT(t, condition, time.Second, time.Millisecond)

pkg/epp/backend/metrics/types.go

@@ -42,12 +42,13 @@ type PodMetricsFactory struct {
 func (f *PodMetricsFactory) NewPodMetrics(parentCtx context.Context, in *corev1.Pod, ds Datastore) PodMetrics {
 	pod := toInternalPod(in)
 	pm := &podMetrics{
-		pmc:      f.pmc,
-		ds:       ds,
-		interval: f.refreshMetricsInterval,
-		once:     sync.Once{},
-		done:     make(chan struct{}),
-		logger:   log.FromContext(parentCtx).WithValues("pod", pod.NamespacedName),
+		pmc:       f.pmc,
+		ds:        ds,
+		interval:  f.refreshMetricsInterval,
+		startOnce: sync.Once{},
+		stopOnce:  sync.Once{},
+		done:      make(chan struct{}),
+		logger:    log.FromContext(parentCtx).WithValues("pod", pod.NamespacedName),
 	}
 	pm.pod.Store(pod)
 	pm.metrics.Store(newMetricsState())