Isolate others from the effect of your work until you are ready. Code is shared via the repository. The build machine is an unattended server that simply gets all of the latest source code from the repository, builds, and tests it, over and over again. The result of this build is the product release.
Tip 2: Stay in the sandbox
Luckily, I've been in environments that used an SCM and some even ran CI servers. None of them, however, consistently ran tests as part of the build but I can see the benefit of doing so.