To amplify David's point, why is the argument a Mapper.Context rather than MapContext?
Also, why is the Mapper.Context not static? On Wed, Jul 22, 2009 at 5:29 PM, David Hall <d...@cs.stanford.edu> wrote: > This is nice, but doesn't it suffer from the same problem? MRUnit uses > the mapred API, which is deprecated, and the new API doesn't use > OutputCollector, but a non-static inner class. > > -- David > > On Wed, Jul 22, 2009 at 4:52 PM, Aaron Kimball<aa...@cloudera.com> wrote: > > Hi David, > > > > I wrote a contrib module called MRUnit > > (http://issues.apache.org/jira/browse/hadoop-5518) designed to allow > > unit tests for mappers/reducers more easily. It's slated for inclusion > > in 0.21, not 0.20 unfortunately, but you can download the patch above > > as well as MAPREDUCE-680 and build it against any earlier version of > > Hadoop. Unfortunately, it doesn't currently support the new APIs > > (e.g., with Context objects), but I imagine this could be added with > > little difficulty. I just haven't had time to do it myself ;) If you'd > > like to take a stab at it, I'd love some help! > > > > More info is at www.cloudera.com/hadoop-mrunit > > Cheers, > > - Aaron > > > > On Wed, Jul 22, 2009 at 2:49 PM, David Hall<d...@cs.stanford.edu> wrote: > >> 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 > >> > > > -- Ted Dunning, CTO DeepDyve
