List list = new ArrayList();
for (Object value : values)
{
list.add(createWritable(value, reducer.getValueInType()));
}
ReduceDriver reduceDriver = new ReduceDriver<Text, LongWritable, Text, LongWritable>();
reduceDriver.withInput(createWritable(key, reducer.getKeyInType()), list);
reduceDriver.setReducer(reducer);
List results = reduceDriver.run();
Collections.sort(results, PairComparer.INSTANCE);
String header = String.format("(%s, %s)\r\n\r\n -> reduces via %s to -> \r\n", key, list, reducer.getClass()
.getSimpleName());
Approvals.verifyAll(header, results, Echo.INSTANCE);
}