Validate the proposed sub-operator test framework, by creating low-level unit tests for the managed version of the external sort.
The external sort has a small number of existing tests, but those tests are quite superficial; the "managed sort" project found many bugs. The managed sort itself was tested with ad-hoc system-level tests created using the new "cluster fixture" framework. But, again, such tests could not reach deep inside the sort code to exercise very specific conditions.
As a result, we spent far too much time using QA functional tests to identify specific code issues.
Using the sub-opeator unit test framework, we can instead test each bit of functionality at the unit test level.
If doing so works, and is practical, it can serve as a model for other operator testing projects.