Another key element in ensuring seamless, continuous deployment is continuous integration (CI), the software development process where developers integrate new code into the code base throughout the development cycle.
In order for automation of deployment processes to work, all the developers working on a project need an efficient way of communicating the changes that take place. Continuous integration makes this possible.
Typically, when working on the same software development project, developers work off of individual copies of a main branch of code. However, functionality issues and bugs can occur after developers merge their changes onto the main codebase, especially when developers work independently from each other. The longer they work independently, the higher the risk.
With CI, everyone merges their code changes into a repository at least once per day. As updates occur, automated build tests run to ensure that any changes remain compatible with the main branch. This process is a fail-safe method for catching integration problems as quickly as possible.
For instance, unit tests validate individual components or functions, providing immediate feedback on code behavior. Integration tests assess interactions between software components and modules to ensure they're working together correctly and catch any issues unit tests might miss.