Integration Testing: In Integration testing, more the one system's modules are combined and tested together to check data flow from one module to another.
Integration Testing Approaches:
1. Big Bang: Where all of the modules are combined together and tested as single system. In this approach tester test only data flow between integrated parts not the entire system as done in the system testing. 2. Top Down: In this approach top level modules (units) are tested before and then step by step the lower level modules (units) are tested. Generally we follow this approach if top down model is used for development. Their Stubs are used to simulate lower level module to test top level module if lower level module are not been implemented in the initial phase. 3. Bottom Up: In this approach bottom level modules (units) are tested before the upper level modules (units) and step by step modules are tested from bottom to up. We follow this approach if bottom to up approach is also followed in development as well. Their Drivers are used to simulate upper level module to test lower level module that may not be available during the initial phase. 4.Sandwich/Hybrid: In this approach we use Top Down and Button Up approaches together to perform integration testing.