It would help if there is some option provided wherein one can test the outcome of a formula during build itself rather than creating dummy workflows with dummy data to test same.
For instance, there can be a dynamic window, which generates input fields based on those selected as part of actual 'Formula', one can provide test values over there and click some 'Test' kind of button to check the output within the tool itself.
This would also be very handy when writing big/complex formulas involving regular expression, so that a user can test her formula without having to
switch screens to third party on the fly testing tools, or running of entire original workflow, or creating test workflows.