Is there a term for this systematic approach? I do it too, in software, and hone in on the right behavior using unit tests - especially to account for idiosyncr

Is there a term for this systematic approach? I do it too, in software, and hone in on the right behavior using unit tests - especially to account for idiosyncratic off by one errors. Basically: get the structure right and then re-align the implementation to meet the expected behavior.