Map m = mock(Map.class);
when(session.getAttribute(RequestFilter.IN_FLIGHT_REQUESTS)).thenReturn(m);
// run
IoFuture f = rq.request(session, r, 12345);
// verify
Assert.assertFalse(f.isDone());
Assert.assertFalse(f.isCancelled());
verify(r, times(2)).requestId();
verify(session).write(r);
verify(m).put("ID", f);
verify(session).getAttribute(RequestFilter.IN_FLIGHT_REQUESTS);