mockkubeapiserver: /apis discovery does not include core group

This avoids an error where clients try to request the /apis/v1
endpoint.

applylib/applyset/applyset_test.go

@@ -71,7 +71,7 @@ data:
 	parentGVK := parent.GroupVersionKind()
 	restmapping, err := h.RESTMapper().RESTMapping(parentGVK.GroupKind(), parentGVK.Version)
 	if err != nil {
-		h.Fatalf("error building parent restmappaing: %v", err)
+		h.Fatalf("error building parent restmapping: %v", err)
 	}
 	s, err := New(Options{
 		Parent:        NewParentRef(parent, "test", "default", restmapping),

mockkubeapiserver/apigrouplist.go

@@ -32,6 +32,10 @@ type apiGroupList struct {
 func (r *apiGroupList) Run(ctx context.Context, s *MockKubeAPIServer) error {
 	groupMap := make(map[string]*metav1.APIGroup)
 	for _, resource := range s.storage.AllResources() {
+		if resource.Group == "" {
+			// core API does not appear in this list
+			continue
+		}
 		group := groupMap[resource.Group]
 		if group == nil {
 			group = &metav1.APIGroup{Name: resource.Group}