Incremental approach: Incremental approach includes following methods:
a. Top down approach
b. Bottom Up approach
c. Sandwich approach
Big Bang Approach:
In Big Bang approach, all the units are integrated together and then tested. The system is not tested until all the modules are ready. When all the modules are ready then they are integrated and tested. Big Bang Integration testing is also known as Usage Model Testing.
In Incremental approach, two or more modules are joined logically and then tested. Stubs and Drivers are used in this testing approach.
Top down approach: In this approach, the main module is broken down into sub-modules and Stubs are used for testing in this approach.
Bottom Up approach: In this approach, the lower modules are tested first and then the higher modules are tested. Drivers are used for testing in this approach.
Sandwich approach : It is the combination of Top-down and Bottom-up approach. In this approach, no Stubs and Drivers are used.