Top-Down Testing
Top-down testing is a software testing strategy where testing begins with the highest-level modules (e.g., main program or user interface) and progressively moves to lower-level modules, using stubs to simulate the behavior of untested lower-level components. It focuses on verifying the integration and functionality of the system from a user's perspective early in the development cycle. This approach helps identify major design flaws and interface issues before detailed unit testing of individual components.
Developers should use top-down testing when working on complex systems with well-defined high-level architectures, as it allows for early validation of critical user-facing features and integration paths. It is particularly useful in projects where the main control logic or user interface is developed first, enabling testing to proceed even if lower-level modules are incomplete. This methodology reduces the risk of late-stage integration failures and aligns well with incremental or iterative development models like Agile.