Thanks a lot Aaron,

I was looking into it, I just hope, it will be compliant with 0.20.2 ...

Otherwise, I am stuck :(


Aaron Kimball a écrit :

You might want to check out MRUnit. It's a unit test harness that contains
mock objects for the context & other associated classes, and works with

It's included in the (unreleased) Hadoop 0.21, as well as Cloudera's
Distribution for Hadoop. See
http://archive.cloudera.com/docs/mrunit/index.html for MRUnit documentation.

- Aaron
On Thu, May 27, 2010 at 9:13 AM, Varene Olivier wrote:

I am on Hadoop 0.20.2, JUnit 4

Varene Olivier a écrit :

Hello to all,
first of all many thanks for this great piece of software you are all
contributing to :)

I am actually creating a program in Hadoop MapReduce, but I intend to
massively use JUnit Tests to validate my code.

To test a Mapper, I mock a Mapper.Context object and run the Mapper.map
function with it, but inside my Mapper.map function, I am using Counters
to maintain internal statistics. The update of those counters make the test
fails with a null pointer (JavaNullPointerException).
There is an issue "Counters" of variable visibility from my test ...

Do you have any idea how to mock/validate/overcome this issue ?

Thanks a lots
Best Regards
Olivier Varene

: Code :

private static enum Counters {NBLINES};
private static IntWritable one = new IntWritable(1);
private static LongWritable oneL = new LongWritable(1);

// Mapper
* outputs 1 for each line encountered
public static class LCMapper extends
Mapper<LongWritable, Text, IntWritable, LongWritable>
private final static IntWritable one = new IntWritable(1);
private final static LongWritable oneL = new LongWritable(1);
* for each line encountered outputs 1 for the key 1
public void map(LongWritable p_key, Text p_inputs, Context p_context)
throws IOException, InterruptedException
p_context.write(one,oneL); } // end map
} // end Mapper

: Test :

public void testLCMapper() throws IOException, InterruptedException
{ LCMapper mapper = new LCMapper();
Text value = new Text("ligneA\nlignB\n");
// mock the map job execution context
Context context = mock(Context.class);
try {
mapper.map(null, value, context);
} catch (NullPointerException e)
// exception raised by context.getCounter(...) null pointer
// HOW TO MOCK ???
// Counter is a static enum from the englobing class ...
// issue with variable visibility (from map function) in this test
// verify that the Mapper issued (one,oneL) pair
} // end testLCMapper

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postedMay 27, '10 at 8:34a
activeMay 28, '10 at 12:48p

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Varene Olivier: 4 posts Aaron Kimball: 1 post



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