.newMultipleInputMapReduceDriver(new IdentityReducer<Text, Object>());
Mapper<Text, Object, Text, Object> identity = new IdentityMapper<Text, Object>();
testDriver.addMapper(identity);
Text k1 = new Text("foo");
Object v1 = new UncomparableWritable(1);
testDriver.withInput(identity, k1, v1);
ReverseIdentityMapper<Object, Text> reverse = new ReverseIdentityMapper<Object, Text>();
testDriver.addMapper(reverse);
Text k2 = new Text("bar");
Object v2 = new UncomparableWritable(2);
testDriver.withInput(reverse, v2, k2);
testDriver.withOutput(k1, v1).withOutput(k2, v2);
testDriver.runTest(false);