layer1: add namespace manager subscribers step 9

pkg/utils/namespace_manager_test.go

@@ -6,6 +6,14 @@ import (
 	"time"
 )
 
+type testNamespaceSubscriber struct {
+	name string
+}
+
+func (s testNamespaceSubscriber) Name() string {
+	return s.name
+}
+
 func TestNamespaceManagerSnapshotAndGet(t *testing.T) {
 	manager := NewNamespaceManager()
 	now := time.Now().UTC()
@@ -93,4 +101,16 @@ func TestNamespaceManagerSnapshotRecordsReturnsCopies(t *testing.T) {
 	if record.RegisteredParts["router"].State != "active" {
 		t.Fatalf("expected part states to be detached copies")
 	}
+}
+
+func TestNamespaceManagerSubscribers(t *testing.T) {
+	manager := NewNamespaceManager()
+	manager.Subscribe(testNamespaceSubscriber{name: "router"})
+	manager.Subscribe(testNamespaceSubscriber{name: "buildermgr"})
+	manager.Subscribe(testNamespaceSubscriber{name: "router"})
+
+	expected := []string{"buildermgr", "router"}
+	if !reflect.DeepEqual(expected, manager.SnapshotSubscribers()) {
+		t.Fatalf("expected subscribers %v, got %v", expected, manager.SnapshotSubscribers())
+	}
 }