Top-down incremental integration entails testing modules from top to bottom in accordance with the architectural plan while controlling flow.
Bottom-up integration — This style of integration testing is performed from the bottom up.
In Incremental Integration Testing, engineers integrate modules one by one using stubs and drivers to find flaws in the product. In this case, each module has a specific job to play in the project or product hierarchy and has well defined dependencies that are only recognized at runtime.
Integration testing, often known as integration and testing (I&T), is a sort of software testing that involves testing the many units, modules, or components of a software program as a whole. These modules, however, may have been created by separate programmers.
The incremental testing approach has the advantage of detecting faults early in a smaller assembly when the cause is relatively easy to identify. Another advantage is that all programs are merged one at a time, with a test performed after each step.
Top-down testing is a type of incremental integration testing approach in which testing is performed by integrating or joining two or more modules from top to bottom via the architecture structure's control flow. In these, high-level modules are tested first, followed by low-level modules.