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https://issues.apache.org/jira/browse/HADOOP-1936?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12533496
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Tom White commented on HADOOP-1936:
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Sorry to come to this so late, but I would vote to use a mock object library
(jMock) to write tests for mappers and reducers as you argued for on the user
list (http://www.mail-archive.com/[EMAIL PROTECTED]/msg02261.html). Using jMock
is much more concise than the approach in this patch (see
http://www.matthewekent.com/?p=15), although I admit it does have a bit of a
learning curve.
> WordCount unit test plus a helper class to facilitate testing Mappers and
> Reducers
> ----------------------------------------------------------------------------------
>
> Key: HADOOP-1936
> URL: https://issues.apache.org/jira/browse/HADOOP-1936
> Project: Hadoop
> Issue Type: Test
> Components: examples
> Reporter: Kate Rhodes
> Priority: Trivial
> Attachments: WordCountTestExampleAndOutputCollectorTestHelper.patch
>
>
> There are to pieces to this The first is a test for WordCount, not because
> word count actually needed one but because it would be useful to beginners to
> have an example of how to unit test Mappers and Reducers.
> The second piece is AOutputCollector and it's associated unit test
> TestAOutputCollector. This is an abstract class that can be quickly extended
> by a stub OutputCollector in your unit tests to collect the output from your
> Mapper and Reducer tests and make it available for easy retreival when
> testing to see if the fourth key that was emitted was the one you expected.
> I think that this would be a useful tool to have in the main test folder but
> wasn't sure where would be best to put it. Also, since nothing else in Hadoop
> uses Hungarian notation you'll probably want to rename it. I didn't because
> I'm not confident about the naming conventions here and figured that since it
> and its test probably wouldn't end up living in the same folder as WordCount
> that you could just rename it when you moved it.
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