Integration testing is black box testing. Integration testing focuses on the interfaces between units, to ensure that units work together to complete a specify task. The purpose of integration testing is to confirm that different components of the application interact with each other. Test cases are developed with the purpose of exercising the interfaces between the components. Integration testing is considered complete, when actual results and expected results are same. Integration testing is done after unit testing. There are mainly three approaches to do integration testing:
• Top-down Approach tests the components by integrating from top to bottom.
• Bottom-up approach It takes place from the bottom of the control flow to the higher level components.
• Big bang approach In this are different module are joined together to form a complete system and then testing is performed on it.