Testing Level - Integration Testing

2) Integration Testing

"Testing two or more modules or functions together with the intent of finding interface defects between the modules/functions."

"Integration testing is a systematic technique for constructing the program structure while at the same time conducting tests to uncover errors associated with interfacing. The objective is to take unit tested components and build a program structure that has been dictated by design."

Once the modules are developing the developers will develop some interfaces and integrate the module with the help of those interfaces while integration they will check whether the interfaces are working fine or not. It is a white box testing and usually developers or white box testers perform it.

The developers will be integrating the modules in any one of the following approaches:

i) Top Down Approach (TDA)
In this approach the parent modules are developed first and then integrated with child modules.

ii) Bottom Up Approach (BUA)
In this approach the child modules are developed first and the integrated that to the corresponding parent modules.

iii) Hybrid Approach
This approach is a mixed approach of both Top down and Bottom up approaches.

iv) Big Bang Approach
Once all the modules are ready at a time integrating them finally is known as big bang approach.



By making unit testing for each module as explained above the process of integrated testing as a whole becomes simpler. This is because by correcting mistakes or bugs in each module the integration of all units as a system and testing process becomes easier. So one might think why the integration is testing needed. The answer is simple. It is needed because unit testing as explained test and assures correctness of only each module. But it does not cover the aspects of how the system would behave or what error would be reported when modules are integrated. This is done in the level of integration testing.

STUB
While integrating the modules in top down approach if at all any mandatory module is missing then that module is replace with a temporary program known as "STUB."

DRIVER
While integrating the modules in bottom up approach if at all any mandatory module is missing then that module is replace with a temporary program known as "DRIVER."