layer1: add namespace manager summary

pkg/utils/namespace_manager_test.go

@@ -59,6 +59,10 @@ func TestNamespaceManagerSnapshotAndGet(t *testing.T) {
 	if record.Name != "tenant-a" || record.Phase != NamespacePhaseDiscovered {
 		t.Fatalf("unexpected record returned: %+v", record)
 	}
+	summary := manager.Summary()
+	if summary.TotalNamespaces != 2 {
+		t.Fatalf("expected summary total namespaces to be 2, got %d", summary.TotalNamespaces)
+	}
 }
 
 func TestNamespaceManagerUpsertIncrementsGeneration(t *testing.T) {
@@ -448,6 +452,29 @@ func TestPrepareManagedNamespaceWatcher(t *testing.T) {
 	}
 }
 
+func TestNamespaceManagerSummary(t *testing.T) {
+	manager := NewNamespaceManager()
+	manager.Upsert(NamespaceEvent{Type: NamespaceEventAdd, Name: "tenant-a", Source: NamespaceSourceWatcher})
+	manager.Upsert(NamespaceEvent{Type: NamespaceEventAdd, Name: "tenant-b", Source: NamespaceSourceWatcher})
+	_, _ = manager.MarkPartRegistering("tenant-a", "router")
+	manager.Upsert(NamespaceEvent{Type: NamespaceEventRemove, Name: "tenant-b", Source: NamespaceSourceWatcher})
+	manager.Subscribe(&testNamespaceSubscriber{name: "router"})
+
+	summary := manager.Summary()
+	if summary.TotalNamespaces != 2 {
+		t.Fatalf("expected total namespaces 2, got %d", summary.TotalNamespaces)
+	}
+	if summary.PhaseCounts[NamespacePhaseRegistering] != 1 {
+		t.Fatalf("expected one registering namespace")
+	}
+	if summary.PhaseCounts[NamespacePhaseRemoved] != 1 {
+		t.Fatalf("expected one removed namespace")
+	}
+	if !reflect.DeepEqual([]string{"router"}, summary.Subscribers) {
+		t.Fatalf("expected router subscriber in summary")
+	}
+}
+
 func TestNamespaceManagerDispatchAdd(t *testing.T) {
 	manager := NewNamespaceManager()
 	manager.Upsert(NamespaceEvent{Type: NamespaceEventAdd, Name: "tenant-a", Source: NamespaceSourceWatcher})