On every project we make heavy use of source control: feature branches, test and release branches, automated merging, cloud-hosted repositories, wired into the same pipeline that runs the tests. Your investment is safeguarded — our entire operation could burn to the ground and the source code would be safe — and the process of building is faster and less risky for it.
The same applies to testing. Unit test frameworks and test-driven design, API testing, UI testing, containerised automated runs, performance testing, and a pipeline that ties them together.
Two things work against a system that simply behaves: time lost to repetitive tasks that invite human error, and regression. Continuous integration is the discipline of refusing to pay for either one twice.
The highest praise in software development is, “It just works.”