Top-Down Integration
Top-down integration is a software testing and integration strategy where higher-level modules are integrated and tested first, while lower-level modules are simulated using stubs. It follows a hierarchical approach, starting from the main or root module and progressively integrating downward to subordinate modules. This method is commonly used in structured or modular software development to verify system architecture and control flow early in the integration process.
Developers should use top-down integration when they need to test critical high-level functionality and system architecture early in the development cycle, such as in projects with well-defined hierarchical structures or when the main control logic is a priority. It is particularly useful for identifying major design flaws quickly and for incremental development where lower-level modules are not yet fully implemented, as stubs can temporarily replace them. This approach is often applied in waterfall or structured development models to ensure that the overall system flow works correctly before detailed components are integrated.