What purpose does dependency injection serve in Sitecore applications?

Dependency injection serves a crucial role in Sitecore applications by promoting modularity and making testing easier. It allows for the decoupling of component dependencies, which means that classes and services can be developed, tested, and maintained independently of one another. This modularity is beneficial because it encourages the use of single-responsibility principles, making it easier to manage code changes, implement new features, and refactor existing code without affecting other components.

In the context of testing, dependency injection enables developers to substitute real dependencies with mock objects, allowing for more straightforward unit tests. This leads to more reliable software since each component can be tested in isolation. Ultimately, leveraging dependency injection results in cleaner, more maintainable code within Sitecore applications.

The other options do not align with the primary purpose of dependency injection. Reducing database size pertains to data management and optimization rather than code structure. Enhancing graphic design capabilities is outside the scope of dependency injection, which is focused on code architecture. Lastly, while dependency injection may streamline some coding processes, it does not eliminate the need for coding altogether, as developers still need to write code to define the behaviors and interactions of their application components.