### Question:
ConfigurationImpl implements Configuration { @Override public Collection<MemberName> getUniqueMemberNamesForAllShards() { Set<MemberName> allNames = new HashSet<>(); for (String shardName: getAllShardNames()) { allNames.addAll(getMembersFromShardName(shardName)); } return allNames; } ConfigurationImpl(final String moduleShardsConfigPath, final String modulesConfigPath);  ConfigurationImpl(final ModuleShardConfigProvider provider); @Override Collection<String> getMemberShardNames(final MemberName memberName); @Override String getModuleNameFromNameSpace(final String nameSpace); @Override ShardStrategy getStrategyForModule(final String moduleName); @Override String getShardNameForModule(final String moduleName); @Override String getShardNameForPrefix(final DOMDataTreeIdentifier prefix); @Override Collection<MemberName> getMembersFromShardName(final String shardName); @Override Set<String> getAllShardNames(); @Override Collection<MemberName> getUniqueMemberNamesForAllShards(); @Override synchronized void addModuleShardConfiguration(final ModuleShardConfiguration config); @Override void addPrefixShardConfiguration(final PrefixShardConfiguration config); @Override void removePrefixShardConfiguration(final DOMDataTreeIdentifier prefix); @Override Map<DOMDataTreeIdentifier, PrefixShardConfiguration> getAllPrefixShardConfigurations(); @Override boolean isShardConfigured(final String shardName); @Override void addMemberReplicaForShard(final String shardName, final MemberName newMemberName); @Override void removeMemberReplicaForShard(final String shardName, final MemberName newMemberName); @Override ShardStrategy getStrategyForPrefix(final DOMDataTreeIdentifier prefix);  }### Answer:
@Test public void testGetUniqueMemberNamesForAllShards() { assertEquals("getUniqueMemberNamesForAllShards", Sets.newHashSet(MEMBER_1, MEMBER_2, MEMBER_3), configuration.getUniqueMemberNamesForAllShards()); }