MRunit: how to test custom sortcomparator? - hadoop

Question

I'm trying to use MRunit to test my sortComparatorClass. It seems MRunit should be able to do this with the setKeyOrderComparator method, but when I run the mapReduceDriver it is not calling the compare() method of SortComparator class.
Pretty sure I'm doing something wrong with MRunit API.
Here's my code for the unit test:
public class UnitTests {
private static transient Log log = LogFactory.getLog(UnitTests.class);
MapReduceDriver<Text, Text, Text, Text, Text, Text> mapReduceDriver;
MapDriver<Text, Text, Text, Text> mapDriver;
ReduceDriver<Text, Text, Text, Text> reduceDriver;
#Before
public void setUp() throws InterruptedException, IOException {
mapDriver = new MapDriver<Text, Text, Text, Text>();
mapDriver.setMapper(new TestMapper());
reduceDriver = new ReduceDriver<Text, Text, Text, Text>();
reduceDriver.setReducer(new TestReducer());
mapReduceDriver = new MapReduceDriver(new TestMapper(), new TestReducer());
mapReduceDriver.setKeyOrderComparator(new TestSortCompartor());
}
#Test
public void testSort() throws IOException {
Text inputKey1 = new Text("def");
Text inputKey2 = new Text("abc");
Text inputValue = new Text("BlahBlahBlah");
mapReduceDriver.addInput(inputKey1, inputValue);
mapReduceDriver.addInput(inputKey2, inputValue);
List<Pair<Text, Text>> output = mapReduceDriver.run();
log.info("Got output of size "+output.size()+" with first pair = "+output.get(0).toString());
}
}
And here's my test sortComparator:
public class TestSortCompartor extends WritableComparator{
private static transient Log log = LogFactory.getLog(TestSortCompartor.class);
public TestSortCompartor() {
super(Text.class, true);
}
#SuppressWarnings("rawtypes")
#Override
public int compare(WritableComparable w1, WritableComparable w2) {
log.info("calling compare with key1 = "+w1.toString()+" and key2 "+w2.toString());
return w1.compareTo(w2) * -1;
}
}
When I run the test I get this output:
INFO 2014-01-13 09:34:27,362 [main] (com.gradientx.gxetl.testMR.UnitTests:53) -
Got output of size 2 with first pair = (abc, BlahBlahBlah)
But there's no output from the sortComparator class - and it's not ordering the keys in reverse, so I know my comparator() method is not being called.
Can anyone advise what am I doing wrong? Is it possible to use MRunit to test my own comparator class? Is there a better way to make a unit test for a custom comparator class?
FYI, here are the relevant dependencies from my Pom:
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-core</artifactId>
<version>2.0.0-mr1-cdh4.4.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-client</artifactId>
<version>2.0.0-mr1-cdh4.4.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.apache.mrunit</groupId>
<artifactId>mrunit</artifactId>
<version>1.0.0</version>
<classifier>hadoop2</classifier>
</dependency>