Patch for "WannaCry" ransomware

Hi. I’d like to get some input as to what would be the adequate testing needed to be done upon applying the Microsoft’s patches to windown-based computers?

How much testing would be recommended in terms of testing to ensure that the patch has not negatively impacted the software applications on these computer?

Thanks for your input.

Usually the ‘patched’ software is placed into a sandbox and evuluated using the acceptance criteria of of the original CSV. Once it passes this patched software is then placed on the web server and activated.