### Question:
MapFileOutputFormat extends FileOutputFormat<WritableComparable, Writable> { public static <K extends WritableComparable, V extends Writable> Writable getEntry(MapFile.Reader[] readers, Partitioner<K, V> partitioner, K key, V value) throws IOException { int readerLength = readers.length; int part; if (readerLength <= 1) { part = 0; } else { part = partitioner.getPartition(key, value, readers.length); } return readers[part].get(key, value); }  RecordWriter<WritableComparable, Writable> getRecordWriter(FileSystem ignored, JobConf job,
                                      String name, Progressable progress); static MapFile.Reader[] getReaders(FileSystem ignored, Path dir,
                                            Configuration conf); static Writable getEntry(MapFile.Reader[] readers,
                                  Partitioner<K, V> partitioner,
                                  K key,
                                  V value);  }### Answer:
@SuppressWarnings("static-access") @Test public void testPartitionerShouldNotBeCalledWhenOneReducerIsPresent() throws Exception { MapFileOutputFormat outputFormat = new MapFileOutputFormat(); Reader reader = Mockito.mock(Reader.class); Reader[] readers = new Reader[]{reader}; outputFormat.getEntry(readers, new MyPartitioner(), new Text(), new Text()); assertTrue(!MyPartitioner.isGetPartitionCalled()); }