如何对mongohadoop作业进行单元测试？
我目前的尝试：

public class MapperTest {

    MapDriver<Object, BSONObject, Text, IntWritable> d;

    @Before
    public void setUp() throws IOException {
        WordMapper mapper = new WordMapper();
        d = MapDriver.newMapDriver(mapper);
    }

    @Test
    public void testMapper() throws IOException {

        BSONObject doc = new BasicBSONObject("sentence", "Two words");
        d.withInput(new Text("anykey"), doc );

        d.withOutput(new Text("Two"), new IntWritable(1));
        d.withOutput(new Text("words"), new IntWritable(1));

        d.runTest();
    }
}

产生以下输出：
在org.bson.basicbsonobject类的io.serializations中，没有在conf中实现序列化的适用类
org.apache.hadoop.mrunit.internal.io.serialization.copy（serialization）上的java.lang.illegalstateexception。java:67)在org.apache.hadoop.mrunit.internal.io.serialization.copy（serialization。java:91)位于org.apache.hadoop.mrunit.internal.io.serialization.copywithconf（序列化）。java:104)在org.apache.hadoop.mrunit.testdriver.copy（testdriver。java:608)在org.apache.hadoop.mrunit.testdriver.copypair（testdriver。java:612)在org.apache.hadoop.mrunit.mapdriverbase.addinput（mapdriverbase。java:118)在org.apache.hadoop.mrunit.mapdriverbase.withinput（mapdriverbase。java:207) ...