Paas software updates

  Our organization is weighing the pros and cons of moving some of our applications into an Azure Paas environment. One concern we have is how we will manage our applications when software upgrades are performed on the PaaS infrastructure.

  For example, our site relies on MySQL and a PHP Microsoft Apps hosted application.

  When Microsoft performs an upgrade on MySQL to a newer version, how can we be sure the newer version will not break our application?

  In an IaaS configuration, we would have a QA instance of MySQL, perform the mysql upgrade there, and test in QA to verify the application still works with the new version of MySQL, and then deploy the same upgrade to MySQL in production.

  I am wondering how this works in Microsoft Apps hosting. If Microsoft is performing an upgrade of the platform, how can we test our app with the upgrade before the platform is upgraded in production?

   Thanks