Integration Testing

Integration Testing  is a level of the software testing process where individual units are combined and tested as a group to achieve the objective of Information System.

Is is Necessary to test whether all the modules / functions work together seamlessly and communicate appropriately during execution.

Approaches of Integration Testing :

1. Big Bang is an approach to Integration Testing where all or most of the units are combined together and tested at one go. This approach is taken when the testing team receives the entire software in a bundle. So what is the difference between Big Bang Integration Testing and System Testing?  Well, the former tests only the interactions between the units while the latter tests the entire system.

2. Bottom Up Integration  : It is used to integrate the Components of the software system starting from smallest module/ functon/ program.

Bottom Up is an approach to Integration Testing where bottom level units are tested first and upper level units step by step after that. This approach is taken when bottom up development approach is followed. Test Drivers are needed to simulate higher level units which may not be available during the initial phases.

3. Top Down Integration : is an approach to Integration Testing where top level units are tested first and lower level units are tested step by step after that. This approach is taken when top down development approach is followed. Test Stubs are needed to simulate lower level units which may not be available during the initial phases.

4. Sandwich/Hybrid is an approach to Integration Testing which is a combination of Top Down and Bottom Up approaches.

Example