@Test
 public void hangsOnToSession() {
   String sessionId = store.createSession("bob");
   assertTrue("Should have a session", store.hasSession(sessionId));
 }
 @Test
 public void deletesSession() {
   String sessionId = store.createSession("bob");
   store.deleteSession(sessionId);
   assertFalse("Should not have a session", store.hasSession("bob"));
 }
 @Test
 public void createsSession() {
   String sessionId = store.createSession("bob");
   assertNotNull(sessionId);
 }