@Test
public void testNoStats() throws Exception {

	JobVertexCheckpointsHandler handler = new JobVertexCheckpointsHandler(
			mock(ExecutionGraphHolder.class));
	ExecutionGraph graph = mock(ExecutionGraph.class);
	ExecutionJobVertex vertex = mock(ExecutionJobVertex.class);
	CheckpointStatsTracker tracker = mock(CheckpointStatsTracker.class);
	when(vertex.getGraph()).thenReturn(graph);
	when(graph.getCheckpointStatsTracker()).thenReturn(tracker);
	// No stats
	when(tracker.getOperatorStats(any(JobVertexID.class)))
			.thenReturn(Option.<OperatorCheckpointStats>empty());
	String response = handler.handleRequest(vertex, Collections.<String, String>emptyMap());
	// Expecting empty response
	assertEquals("{}", response);
}