Unit Test MapReduce - Junit Mockito

Question

I am new to writing test cases for Map Reduce and as I googled, I understood that MRUnit is deprecated and have to use Mockito. Could someone provide inspiration on testing mapreduce with Junit mockito as I couldn't find one. I could only see MRUnit test cases for mapreduce.

Answer 1

I am providing a sample test class here for mapper. Test for reducer can also be written in same fashion.

@RunWith(MockitoJUnitRunner.class)
public class SampleMapperTest {

    @Mock
    private Mapper.Context mockContext; // declare your mocks

    @Mock
    Counter mockCounter; // mocked hadoop counter

    SampleMapper mapper;

    @Before
    public void setUp() throws Exception {
       /*
        * mock and define your components here
        */
        mapper = new SampleMapper();
        doNothing().when(mockCounter).increment(anyLong());
    }

    @Test
    public void testMap() throws IOException, InterruptedException {
       /*
        * whatever you want to test you can write here in the verify statement
        */
        String line1 = "key_value";
        mapper.map(null, new Text(line1), mockContext);
        verify(mockCounter, times(1)).increment(1);
    }

    @After
    public void tearDown() throws Exception {
       /*
        * this will do the clean up part
        */
        verifyNoMoreInteractions(mockContext);
    }
}

I hope you get some insight from this and should be able to write your test now.