### Question:
ContainerDBServiceProviderImpl implements ContainerDBServiceProvider { @Override public void deleteContainerMapping(ContainerKeyPrefix containerKeyPrefix) throws IOException { containerKeyTable.delete(containerKeyPrefix); } @Inject  ContainerDBServiceProviderImpl(DBStore dbStore,
                                        Configuration sqlConfiguration); @Override void close(); @Override void initNewContainerDB(Map<ContainerKeyPrefix, Integer>
                                     containerKeyPrefixCounts); @Override void storeContainerKeyMapping(ContainerKeyPrefix containerKeyPrefix,
                                       Integer count); @Override void storeContainerKeyCount(Long containerID, Long count); @Override long getKeyCountForContainer(Long containerID); @Override boolean doesContainerExists(Long containerID); @Override Integer getCountForContainerKeyPrefix(
      ContainerKeyPrefix containerKeyPrefix); @Override Map<ContainerKeyPrefix, Integer> getKeyPrefixesForContainer(
      long containerId); @Override Map<ContainerKeyPrefix, Integer> getKeyPrefixesForContainer(
      long containerId, String prevKeyPrefix); @Override Map<Long, ContainerMetadata> getContainers(int limit,
                                                    long prevContainer); @Override void deleteContainerMapping(ContainerKeyPrefix containerKeyPrefix); @Override long getCountForContainers(); @Override TableIterator getContainerTableIterator(); @Override void storeContainerCount(Long count); @Override void incrementContainerCountBy(long count);  }### Answer:
@Test public void testDeleteContainerMapping() throws Exception { long containerId = 1L; long nextContainerId = 2L; populateKeysInContainers(containerId, nextContainerId); Map<ContainerKeyPrefix, Integer> keyPrefixMap = containerDbServiceProvider.getKeyPrefixesForContainer(containerId); assertEquals(2, keyPrefixMap.size()); containerDbServiceProvider.deleteContainerMapping(new ContainerKeyPrefix( containerId, keyPrefix2, 0)); keyPrefixMap = containerDbServiceProvider.getKeyPrefixesForContainer(containerId); assertEquals(1, keyPrefixMap.size()); }