MRUnit test for testing hadoop map program error

Question

I'm trying to unit test a Mapper program using MRUnit (from Hadoop:The definitive guide book, page 153, section: Writing a unit test with MRUnit: Mapper). I'm using intellij Idea and it is showing an error in method

new org.apache.hadoop.mrunit.MapDriver<>().withMapper(myMapper)

The error message says, withMapper(org.apache.hadoop.mapreduce.Mapper) in MapDriver cannot be applied to (complexmapreduce.MaxTempMapper )

MaxTempMapper is declared as a subclass of org.apache.hadoop.mapreduce.Mapper , so I'm not really sure what is wrong here.

Here are the complete Mapper and Unit test classes

MaxTempMapper

package complexmapreduce;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Mapper;
import java.io.IOException;

public class MaxTempMapper extends Mapper<LongWritable, Text, Text, IntWritable> {
    private static final int MISSING = 9999;
    private NDCRecordParser myParser = new NDCRecordParser();

    @Override
    public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {

        myParser.parse(value);
        if (myParser.isValidTemperature()) {
            context.write(new Text(myParser.getYear()), new IntWritable(myParser.getMaxTemperature()));
        }
    }
}

MaxTempUnitTest

    package complexmapreduce;
    import org.apache.hadoop.io.IntWritable;
    import org.apache.hadoop.io.LongWritable;
    import org.apache.hadoop.io.Text;
    import org.junit.Test;
    import java.io.IOException;

    public class MaxTempSingleLineUnitTest {

        @Test
        public void testMaxTempMapper() throws IOException {
            Text value = new Text("0029029070999991901010106004+64333+023450FM-12+000599999V0202701N015919999999N0000001N9-00781+99999102001ADDGF108991999999999999999999");
            LongWritable key = new LongWritable(0);
            MaxTempMapper myMapper = new MaxTempMapper();
            new org.apache.hadoop.mrunit.mapreduce.MapDriver<>()
                    .withMapper(myMapper)     // <<<===Error here
                    .withInput(key, value)
                    .withOutput(new Text("1901"), 
                     new IntWritable(0210))
                    .runTest();
        }
    }

Note: Already tried the solution here, but no luck.

Here is a screenshot from Intellij

Screenshot

Answer 1

You need to change:

new org.apache.hadoop.mrunit.mapreduce.MapDriver<>()

to

new org.apache.hadoop.mrunit.mapreduce.MapDriver<LongWritable, Text, Text, IntWritable>()

You need to add the generic types so that it knows how to run the mapper.