fix: Update unit test to catch actual nil Labels case and fix functionality to handle nil Labels

Kubernetes-commit: 4ae3b64b73617c9f9f162874e87f500e265f05e1

Author: DerekFrank

tools/leaderelection/resourcelock/leaselock.go

@@ -77,6 +77,9 @@ func (ll *LeaseLock) Update(ctx context.Context, ler LeaderElectionRecord) error
 	ll.lease.Spec = LeaderElectionRecordToLeaseSpec(&ler)
 
 	if ll.Labels != nil {
+		if ll.lease.Labels == nil {
+			ll.lease.Labels = map[string]string{}
+		}
 		// Only overwrite the labels that are specifically set
 		for k, v := range ll.Labels {
 			ll.lease.Labels[k] = v

tools/leaderelection/resourcelock/leaselock_test.go

@@ -266,7 +266,7 @@ func TestLeaseConversion(t *testing.T) {
 	}
 }
 
-func TestUpdateWithNilLabels(t *testing.T) {
+func TestUpdateWithNilLabelsOnLease(t *testing.T) {
 	setup()
 
 	// Create initial lease
@@ -278,23 +278,30 @@ func TestUpdateWithNilLabels(t *testing.T) {
 		t.Fatalf("Failed to get lease: %v", err)
 	}
 
-	leaseLock.lease.Labels = map[string]string{"custom-key": "custom-val"}
+	leaseLock.Labels = map[string]string{"custom-key": "custom-val"}
 
-	// Update labels
-	lease, err := leaseLock.Client.Leases(testNamespace).Update(context.Background(), leaseLock.lease, metav1.UpdateOptions{})
-	if err != nil {
-		t.Fatalf("Failed to update lease labels: %v", err)
+	// Update should succeed even with nil Labels on the lease itself
+	if err := leaseLock.Update(context.Background(), testRecord); err != nil {
+		t.Errorf("Update failed with nil Labels: %v", err)
 	}
+}
 
-	val, exists := lease.Labels["custom-key"]
-	if !exists {
-		t.Error("Label was overidden on the lease")
+
+func TestUpdateWithNilLabelsOnLeaseLock(t *testing.T) {
+	setup()
+
+	// Create initial lease
+	if err := leaseLock.Create(context.Background(), testRecord); err != nil {
+		t.Fatalf("Failed to create lease: %v", err)
 	}
-	if val != "custom-val" {
-		t.Errorf("Label value mismatch, got %q want %q", val, "custom-val")
+	// Get the lease to initialize leaseLock.lease
+	if _, _, err := leaseLock.Get(context.Background()); err != nil {
+		t.Fatalf("Failed to get lease: %v", err)
 	}
 
-	// Update should succeed even with nil Labels
+	leaseLock.lease.Labels = map[string]string{"custom-key": "custom-val"}
+
+	// Update should succeed even with nil Labels on the leaselock
 	if err := leaseLock.Update(context.Background(), testRecord); err != nil {
 		t.Errorf("Update failed with nil Labels: %v", err)
 	}
@@ -364,4 +371,4 @@ func TestLabelUpdate(t *testing.T) {
 	if val != "custom-val-2" {
 		t.Errorf("Label value mismatch, got %q want %q", val, "custom-val-2")
 	}
-}
+}