### Question:
CassandraStore implements DataStore<K, T> { @Override public long deleteByQuery(Query<K, T> query) throws GoraException { return cassandraSerializer.deleteByQuery(query); } CassandraStore(); @Override void initialize(Class<K> keyClass, Class<T> persistentClass, Properties properties); @SuppressWarnings("all") @Override Class<T> getPersistentClass(); @Override void setPersistentClass(Class<T> persistentClass); @Override String getSchemaName(); @Override void createSchema(); @Override void deleteSchema(); @SuppressWarnings("all") @Override Class<K> getKeyClass(); @Override void setKeyClass(Class<K> keyClass); @Override K newKey(); @SuppressWarnings("all") @Override T newPersistent(); @Override BeanFactory<K, T> getBeanFactory(); @Override void setBeanFactory(BeanFactory<K, T> beanFactory); @Override void close(); @Override T get(K key); @Override T get(K key, String[] fields); @Override void put(K key, T obj); @Override boolean delete(K key); @Override long deleteByQuery(Query<K, T> query); @Override Result<K, T> execute(Query<K, T> query); boolean updateByQuery(Query<K, T> query); @Override Query<K, T> newQuery(); @Override List<PartitionQuery<K, T>> getPartitions(Query<K, T> query); @Override void flush(); @Override boolean equals(Object obj); @Override void truncateSchema(); @Override boolean schemaExists(); @Override boolean exists(K key);  }### Answer:
@Test public void testDeleteByQuery() throws Exception { preConfiguration(); log.info("test method: testDeleteByQuery"); DataStore store = webPageStore; Query<String, WebPage> query; WebPageDataCreator.createWebPageData(store); query = store.newQuery(); assertNumResults(store.newQuery(), URLS.length); store.deleteByQuery(query); store.flush(); assertEmptyResults(store.newQuery()); store.truncateSchema(); }