A friend of mine built something in the same vein.
" The Problem:
You have complex computations that you want to generatively test, and you can't test for correctness.
The Solution:
Use an LibreOffice Calc Spreadsheet as your 'obviously correct' calculation engine, and test your computations in a format that even your clients will be familiar with. Sounds crazy, but think more on it. A Spreadsheet is one of the most powerful ways to visualise number crunching, and pretty much everyone knows how to use it. If you have a reliable spreadsheet that accepts input data, and outputs data, you have yourself a testable computation that the client can understand.
"