Effective and continuous practice of TDD can improve the code-writing process, making testing easier, which results in improved code quality and robust software application. However, when a project's code base contains portions of codes that are untestable, writing unit or integration tests becomes extremely difficult or nearly impossible.
Software development teams cannot emphatically validate the consistent behavior of the functionalities and features of an application when there is untestable code in a software project's code base. To avoid this preventable situation, writing code that is testable is not an option but a must for every serious development team that values quality software.
Untestable ...
