@Test
 public void testOpenGraph() {
   final String graphName = "graphName";
   manager.addGraph(graphName);
   assertNotNull(managedGraphs.get(graphName));
   assertNotNull(manager.openGraph(graphName));
 }
 @Test
 public void testOpenGraphGraphManagerGraph() {
   assertNotNull(manager.openGraph(GraphManagerGraphFilterGraph.GRAPH_MANAGER_GRAPH_NAME));
 }