Hi, I'm a student working with Apache Mahout for the Google Summer of Code. We recently moved to 0.20.0, and I was porting my code to the new API. Unfortunately, I (and the whole project team) seem to have run into a problem when it comes to testing them.
Historically, we would create a Mapper in a unit test, and a special "DummyOutputCollector", which was essentially a multimap dressed up to conform to OutputCollector. In Hadoop 0.20.0, this isn't possible anymore, because Mappers take an instance of an inner class. It's of course possible to dress up the Context in something else (say, something just like an OutputCollector), and to specify that Mahout Mappers should just delegate to a method that takes an OutputCollector. But, this seems to not be very idiomatic. All this goes to say, what would be a "best practice" for testing Mappers and Reducers in 0.20.0? Thanks, David Hall
