@Before
 public void setUp() throws Exception {
   cluster = CassandraUnitUtils.cassandraCluster();
   session = cluster.connect(CassandraUnitUtils.KEYSPACE);
   idempotentRepository = new CassandraIdempotentRepository<String>(session);
   idempotentRepository.start();
 }
 @Test
 public void testContainsNotExists() {
   // Given
   String key = "Contains_NotExists";
   assertFalse(exists(key));
   // When
   boolean result = idempotentRepository.contains(key);
   // Then
   assertFalse(result);
 }
 @Test
 public void testRemoveExists() {
   // Given
   String key = "Remove_Exists";
   assertTrue(exists(key));
   // When
   boolean result = idempotentRepository.remove(key);
   // Then
   assertTrue(result);
 }
 @Test
 public void testAddExists() {
   // Given
   String key = "Add_Exists";
   assertTrue(exists(key));
   // When
   boolean result = idempotentRepository.add(key);
   // Then
   assertFalse(result);
   assertTrue(exists(key));
 }
 @After
 public void tearDown() throws Exception {
   idempotentRepository.stop();
   session.close();
   cluster.close();
 }