@Test
public void testCombiner() throws Exception {
MessageCombiner<WritableComparable, IntWritable>
messageCombiner =
new MinimumIntMessageCombiner();
IntWritable vertexId = new IntWritable(1);
IntWritable result = messageCombiner.createInitialMessage();
messageCombiner.combine(vertexId, result, new IntWritable(39947466));
messageCombiner.combine(vertexId, result, new IntWritable(199));
messageCombiner.combine(vertexId, result, new IntWritable(42));
messageCombiner.combine(vertexId, result, new IntWritable(19998888));
assertEquals(42, result.get());
}