Comment by scruple

Not fib, but... I've written tests like this semi-recently for an algorithm that I had to devise. I went to Excel to generate the test data, based on a data pull from our production database. So, real production data, using a sequence of Excel spreadsheet functions, which also has multiple eyes on it (including legal, since this was regulatory in nature), fed as input to the algorithm to verify the output matched up.

I'm still on the fence about that but I'm not sure how else to test something that is essentially a glorified algebra formula.