<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 12 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>(This answer has basically been covered already but …)<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I would add that having a regression test suite (unit and integration) creates a behavior contract or boundary (or as Michael Feathers puts it a “vise”) for your program. This gives you the freedom to be able to re-factor legacy code and not be terrified that it will break. The goal is to have the minimum amount of maintainable tests with maximum amount of the coverage of the program’s behavior.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>A good book on the subject is Michael Feather’s “Working Effectively with Legacy Code” where he describes how to do this for OOP and procedural languages like C.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>http://www.amazon.com/Working-Effectively-Legacy-Michael-Feathers/dp/0131177052<o:p></o:p></span></p></div></div></body></html>