if tc.prevConfigs != nil {
				proxy.PrevSidecarScope = &model.SidecarScope{}
				proxy.PrevSidecarScope.SetDestinationRulesForTesting(tc.prevConfigs)
			}
			clusters, removed, delta := cg.DeltaClusters(proxy, tc.configUpdated,
				&model.WatchedResource{ResourceNames: tc.watchedResourceNames})
			if delta != tc.usedDelta {
				t.Errorf("un expected delta, want %v got %v", tc.usedDelta, delta)
			}