### Question:
IndexWriter implements Stoppable { public static IndexCommitter getCommitter(RegionCoprocessorEnvironment env) throws IOException { return getCommitter(env,TrackingParallelWriterIndexCommitter.class); } IndexWriter(RegionCoprocessorEnvironment env, String name);  IndexWriter(IndexFailurePolicy failurePolicy, RegionCoprocessorEnvironment env, String name);  IndexWriter(IndexCommitter committer, IndexFailurePolicy policy,
      RegionCoprocessorEnvironment env, String name);   IndexWriter(IndexCommitter committer, IndexFailurePolicy policy); static IndexCommitter getCommitter(RegionCoprocessorEnvironment env); static IndexCommitter getCommitter(RegionCoprocessorEnvironment env, Class<? extends IndexCommitter> defaultClass); static IndexFailurePolicy getFailurePolicy(RegionCoprocessorEnvironment env); void writeAndKillYourselfOnFailure(Collection<Pair<Mutation, byte[]>> indexUpdates,
            boolean allowLocalUpdates, int clientVersion); void writeAndKillYourselfOnFailure(Multimap<HTableInterfaceReference, Mutation> toWrite,
            boolean allowLocalUpdates, int clientVersion); void write(Collection<Pair<Mutation, byte[]>> toWrite, int clientVersion); void write(Collection<Pair<Mutation, byte[]>> toWrite, boolean allowLocalUpdates, int clientVersion); void write(Multimap<HTableInterfaceReference, Mutation> toWrite, boolean allowLocalUpdates, int clientVersion); @Override void stop(String why); @Override boolean isStopped(); static final String INDEX_COMMITTER_CONF_KEY; static final String INDEX_FAILURE_POLICY_CONF_KEY; }### Answer:
@Test public void getDefaultWriter() throws Exception { Configuration conf = new Configuration(false); RegionCoprocessorEnvironment env = Mockito.mock(RegionCoprocessorEnvironment.class); Mockito.when(env.getConfiguration()).thenReturn(conf); assertNotNull(IndexWriter.getCommitter(env)); }