If you are a CC subscriber, the best way to test the extension is to install a version of DW other than your working version. As an example, my daily version is CC2018. I can also install CC2017 or even the CC Pre-release (found here: https://www.adobeprerelease.com/beta/9EB451B5-D2E8-46E5-AFA2-78C85442FFA2). The latter will allow you to test the extension in a future release of DW.
This way, you can test at heart's content while not interfere with your production.