The class FixedTupleSpout is useful for emitting test tuples in end-to-end topology tests. Unfortunately it appears to only support a single output field, which greatly limits what topologies you can test with.
In the PR, I propose adding a new constructor to FixedTupleSpout to allow specifying more than one field.
I also decided to deprecate the existing constructor which accepts a String due to the fact that it will cause an ambiguity compilation error if the calling code is passing in null, so it should probably be entirely removed at a later point.
I created a PR against master and against the 1.x branch.