Make scheme and cache mandatory when controller is set in object tracker

Author: Karthik-K-N

controllers/external/tracker.go

@@ -49,6 +49,10 @@ func (o *ObjectTracker) Watch(log logr.Logger, obj client.Object, handler handle
 		return nil
 	}
 
+	if o.Cache == nil || o.Scheme == nil {
+		return errors.New("both scheme and cache must be set for object tracker")
+	}
+
 	gvk := obj.GetObjectKind().GroupVersionKind()
 	key := gvk.GroupKind().String()
 	if _, loaded := o.m.LoadOrStore(key, struct{}{}); loaded {

controllers/external/tracker_test.go

@@ -23,6 +23,8 @@ import (
 	. "github.com/onsi/gomega"
 	"github.com/pkg/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"sigs.k8s.io/controller-runtime/pkg/cache/informertest"
 	"sigs.k8s.io/controller-runtime/pkg/controller"
 	"sigs.k8s.io/controller-runtime/pkg/log"
 	"sigs.k8s.io/controller-runtime/pkg/source"
@@ -64,7 +66,7 @@ func (c *watchCountController) Watch(_ source.Source) error {
 func TestRetryWatch(t *testing.T) {
 	g := NewWithT(t)
 	ctrl := newWatchCountController(true)
-	tracker := ObjectTracker{Controller: ctrl}
+	tracker := ObjectTracker{Controller: ctrl, Scheme: runtime.NewScheme(), Cache: &informertest.FakeInformers{}}
 
 	err := tracker.Watch(logger, &clusterv1.Cluster{}, nil)
 	g.Expect(err).To(HaveOccurred())
@@ -78,7 +80,7 @@ func TestRetryWatch(t *testing.T) {
 func TestWatchMultipleTimes(t *testing.T) {
 	g := NewWithT(t)
 	ctrl := &watchCountController{}
-	tracker := ObjectTracker{Controller: ctrl}
+	tracker := ObjectTracker{Controller: ctrl, Scheme: runtime.NewScheme(), Cache: &informertest.FakeInformers{}}
 
 	obj := &clusterv1.Cluster{
 		TypeMeta: metav1.TypeMeta{