fix: List no resources when source namespace is empty string

Previously, the controller listed resources in all namespaces when the
source namespace was an empty string.

Author: dlipovetsky

pkg/controllers/namespacesync/controller.go

@@ -150,6 +150,12 @@ func (r *Reconciler) listSourceClusterClasses(
 	[]clusterv1.ClusterClass,
 	error,
 ) {
+	// Handle the empty string explicitly, because listing resources with an empty
+	// string namespace returns resources in all namespaces.
+	if r.SourceClusterClassNamespace == "" {
+		return []clusterv1.ClusterClass{}, nil
+	}
+
 	ccl := &clusterv1.ClusterClassList{}
 	err := r.Client.List(ctx, ccl, client.InNamespace(r.SourceClusterClassNamespace))
 	if err != nil {

pkg/controllers/namespacesync/controller_test.go

@@ -73,6 +73,29 @@ func TestReconcileNewClusterClass(t *testing.T) {
 	}
 }
 
+func TestSourceClusterClassNamespaceEmpty(t *testing.T) {
+	g := NewWithT(t)
+
+	_, cleanup, err := createUniqueClusterClassAndTemplates(
+		sourceClusterClassNamespace,
+	)
+	g.Expect(err).ToNot(HaveOccurred())
+	defer func() {
+		g.Expect(cleanup()).To(Succeed())
+	}()
+
+	// This test initializes its own reconciler, instead of using the one created
+	// in suite_test.go, in order to configure the source namespace.
+	r := Reconciler{
+		Client:                      env.Client,
+		SourceClusterClassNamespace: "",
+	}
+
+	ns, err := r.listSourceClusterClasses(ctx)
+	g.Expect(err).ToNot(HaveOccurred())
+	g.Expect(ns).To(BeEmpty())
+}
+
 func verifyClusterClassAndTemplates(
 	cli client.Reader,
 	name,