You assume that you will write code and check in without testing. Code should pass all unit tests locally before check in. Some tools, like TFS, can be configured with a gated check in. If unit tests don't pass, check in is prohibited.
>Craig. I often believe the software world can learn from other industries. So using an engine as a mainline branch. A developer wishes to refine the spark plug. That takes months of iterative testing and discarding unworkable designs. Why should any of these unworkable ones reach the mainline branch?
Craig Berntson
MCSD, Microsoft .Net MVP, Grape City Community Influencer