Mastering Object-oriented Python

Using externally defined expected results

For some applications, users can articulate processing rules that describe the software's behavior. In other cases, the job of an analyst or a designer transforms the user's desires into procedural descriptions of the software.

In many cases, it's easier for users to provide concrete examples of expected results. For some business-oriented applications, the users may be more comfortable creating a spreadsheet that shows us sample inputs and expected results. Working from user-supplied, concrete sample data can simplify the developing software.

Whenever possible, have real users produce concrete examples of correct results. Creating procedural descriptions or software specifications is remarkably difficult. ...