1.前言
在寫完MR之後,通常都會自己造一些數據本地測一下保證基本邏輯沒問題。這裏使用MRUnit進行MR的單元測試
官網地址:https://mrunit.apache.org/
這裏笨小蔥使用MRUnit來測試一下最簡單的WordCount的MR代碼。
2.maven配置
<dependency>
<groupId>org.apache.mrunit</groupId>
<artifactId>mrunit</artifactId>
<version>1.0.0</version>
<classifier>hadoop2</classifier>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.10</version>
<scope>test</scope>
</dependency>
3.WordCount代碼
public class WordCount {
public static class WCMap extends Mapper<LongWritable, Text, Text, IntWritable>
{
private Text k=new Text();
private final static IntWritable addOne = new IntWritable(1);
@Override
protected void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
String[] valueArr=value.toString().split(" ");
for (String val:valueArr)
{
k.set(val);
context.write(k,addOne);
}
}
}
public static class WCReduce extends Reducer<Text,IntWritable,Text,IntWritable>
{
private static IntWritable sum=new IntWritable();
@Override
protected void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException {
int count=0;
for(IntWritable i:values)
{
count+=i.get();
}
sum.set(count);
context.write(key,sum);
}
}
}
3.MRunit測試代碼
public class WordCountMRTest {
MapDriver<LongWritable, Text, Text, IntWritable> mapDriver;
ReduceDriver<Text, IntWritable, Text, IntWritable> reduceDriver;
MapReduceDriver<LongWritable, Text, Text, IntWritable, Text, IntWritable> mapReduceDriver;
@Before
public void setUp() {
//測試mapreduce
WordCount.WCMap mapper = new WordCount.WCMap();
WordCount.WCReduce reducer = new WordCount.WCReduce();
mapDriver = MapDriver.newMapDriver(mapper);
reduceDriver = ReduceDriver.newReduceDriver(reducer);
mapReduceDriver = MapReduceDriver.newMapReduceDriver(mapper, reducer);
}
//測試mapper
@Test
public void testMapper() throws IOException {
//output {(a,1),(b,1),(c,1).....}
List<Pair<Text, IntWritable>> outputRecords=new ArrayList<Pair<Text, IntWritable>>();
outputRecords.add(new Pair<Text, IntWritable>(new Text("a"),new IntWritable(1)));
outputRecords.add(new Pair<Text, IntWritable>(new Text("b"),new IntWritable(1)));
outputRecords.add(new Pair<Text, IntWritable>(new Text("c"),new IntWritable(1)));
outputRecords.add(new Pair<Text, IntWritable>(new Text("d"),new IntWritable(1)));
outputRecords.add(new Pair<Text, IntWritable>(new Text("a"),new IntWritable(1)));
//input "a b c d a"
mapDriver.withInput(new LongWritable(), new Text(
"a b c d a"));
mapDriver.withAllOutput(outputRecords);
mapDriver.runTest();
}
//測試mapper
@Test
public void testReducer() throws Exception{
//input {(a,{1,1}),(b,{1,1,1})}
List<Pair<Text, List<IntWritable>>> allInput=new ArrayList<Pair<Text, List<IntWritable>>>();
List<IntWritable> list=new ArrayList<IntWritable>();
list.add(new IntWritable(1));
list.add(new IntWritable(1));
List<IntWritable> list2=new ArrayList<IntWritable>();
list2.add(new IntWritable(1));
list2.add(new IntWritable(1));
list2.add(new IntWritable(1));
allInput.add(new Pair<Text, List<IntWritable>>(new Text("a"),list));
allInput.add(new Pair<Text, List<IntWritable>>(new Text("b"),list2));
//output {(a,2),(b,3)}
List<Pair<Text, IntWritable>> outputRecords=new ArrayList<Pair<Text, IntWritable>>();
outputRecords.add(new Pair<Text, IntWritable>(new Text("a"),new IntWritable(2)));
outputRecords.add(new Pair<Text, IntWritable>(new Text("b"),new IntWritable(3)));
reduceDriver.withAll(allInput);
reduceDriver.withAllOutput(outputRecords);
reduceDriver.runTest();
}
@Test
public void testMR() throws Exception{
//output {(a,2),(b,1),(c,2)}
List<Pair<Text, IntWritable>> outputRecords=new ArrayList<Pair<Text, IntWritable>>();
outputRecords.add(new Pair<Text, IntWritable>(new Text("a"),new IntWritable(2)));
outputRecords.add(new Pair<Text, IntWritable>(new Text("b"),new IntWritable(1)));
outputRecords.add(new Pair<Text, IntWritable>(new Text("c"),new IntWritable(2)));
//input "a b c c a"
mapReduceDriver.withInput(new LongWritable(), new Text("a b c c a"));
mapReduceDriver.withAllOutput(outputRecords);
mapReduceDriver.runTest();
}
}