A picture's worth a 1000 tests.
Unit testing asserts can be difficult to use. Approval tests simplify this by taking a snapshot of the results, and confirming that they have not changed.
PigUnit is a simple xUnit framework that enables you to easily test your Pig scripts. With PigUnit you can perform unit testing, regression testing, and rapid prototyping. No cluster set up is required if you run Pig in local mode.