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MRUnit Example

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WordCountをMRUnitでユニットテストを行うサンプル


依存ライブラリ

MRUnitはclassifierにhadoop1 or hadoop2を指定する必要があります


pom.xml

<dependencies>

<dependency>
<groupId>org.apache.hadoop</groupId>
<artifactId>hadoop-core</artifactId>
<version>1.0.3</version>
</dependency>
<dependency>
<groupId>org.apache.mrunit</groupId>
<artifactId>mrunit</artifactId>
<version>1.1.0</version>
<classifier>hadoop1</classifier>
<scope>test</scope>
</dependency>
</dependencies>


プロダクトコード


WordCount.java

package examples.mrunit;

import java.io.IOException;
import java.util.*;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;

public class WordCount {

public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable>{
private final static IntWritable one = new IntWritable(1);
private Text word = new Text();

@Override
public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
StringTokenizer itr = new StringTokenizer(value.toString());
while (itr.hasMoreTokens()) {
word.set(itr.nextToken());
context.write(word, one);
}
}
}

public static class IntSumReducer extends Reducer<Text,IntWritable,Text,IntWritable> {
private IntWritable result = new IntWritable();

@Override
public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
int sum = 0;
for (IntWritable val : values) {
sum += val.get();
}
result.set(sum);
context.write(key, result);
}
}

public static void main(String[] args) throws Exception {
Configuration conf = new Configuration();
Job job = new Job(conf, "word count");
job.setJarByClass(WordCount.class);
job.setMapperClass(TokenizerMapper.class);
job.setCombinerClass(IntSumReducer.class);
job.setReducerClass(IntSumReducer.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(IntWritable.class);
FileInputFormat.setInputPaths(job, new Path(args[0]));
FileOutputFormat.setOutputPath(job, new Path(args[1]));
System.exit(job.waitForCompletion(true) ? 0 : 1);
}
}



テストコード


WordCountTest.java

package examples.mrunit;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

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 org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mrunit.mapreduce.MapDriver;
import org.apache.hadoop.mrunit.mapreduce.MapReduceDriver;
import org.apache.hadoop.mrunit.mapreduce.ReduceDriver;
import org.junit.Before;
import org.junit.Test;

import examples.mrunit.WordCount.*;

public class WordCountTest {

private Mapper<Object, Text, Text, IntWritable> mapper;
private Reducer<Text, IntWritable, Text, IntWritable> reducer;

private MapDriver<Object, Text, Text, IntWritable> mapDriver;
private ReduceDriver<Text, IntWritable, Text, IntWritable> reduceDriver;
private MapReduceDriver<Object, Text, Text, IntWritable, Text, IntWritable> mapReduceDriver;

@Before
public void setUp(){
mapper = new TokenizerMapper();
reducer = new IntSumReducer();

mapDriver = new MapDriver<Object, Text, Text, IntWritable>(mapper);
reduceDriver = new ReduceDriver<Text, IntWritable, Text, IntWritable>(reducer);
mapReduceDriver = new MapReduceDriver<Object, Text, Text, IntWritable, Text, IntWritable>(mapper, reducer);
}

@Test
public void testMapper() throws IOException{
mapDriver.withInput(new LongWritable(1), new Text("cat cat dog"));
mapDriver.withOutput(new Text("cat"), new IntWritable(1));
mapDriver.withOutput(new Text("cat"), new IntWritable(1));
mapDriver.withOutput(new Text("dog"), new IntWritable(1));
mapDriver.runTest();
}

@Test
public void testReducer() throws IOException{
List<IntWritable> values = new ArrayList<IntWritable>();
values.add(new IntWritable(1));
values.add(new IntWritable(1));
reduceDriver.withInput(new Text("cat"), values);
reduceDriver.withOutput(new Text("cat"), new IntWritable(2));
reduceDriver.runTest();
}

@Test
public void testMapReduce() throws IOException{
mapReduceDriver.withInput(new LongWritable(1), new Text("cat cat dog"));
mapReduceDriver.addOutput(new Text("cat"), new IntWritable(2));
mapReduceDriver.addOutput(new Text("dog"), new IntWritable(1));
mapReduceDriver.runTest();
}
}


pom.xmlとソースコードはgithub上にも置いてあります

https://github.com/ishihamat/MRUnitExample