MAPREDUCE-4118 which was duped to this (Just so it is not lost).
There are a number of tests from MRV1 that are being pulled into MRV2. Many of these tests use MiniMRCluster, but the MiniMRCluser shim was added so that projects like Oozie and Pig can have a single test that will work for either Yarn or MRV1. Internally our tests are never going to go back to be run on MRV1 so we should update them to use the new code.
Also there are some places where older tests and newer tests are almost duplicates of one another, or where the same results are archived through through mock objects. For the sake of runtime of the tests it would be better to remove some of these duplicates.