– When the testing is carried out after combining the individual modules in to groups, it is called integration testing.
– This testing is carried out after the completion of the unit testing but before proceeding with the validation testing.
– The units that have been successful in the unit testing are taken as input in the integration testing and grouped together and then tested.
– The integration tests defined in the test plan are only applied to these unit aggregates.
– The integrated system after successful integration testing is ready to be subjected to system testing.
– The integration testing is used for the verification of the performance, functionality, reliability and requirements and so on.
– These are the requirements based up on the major design items.
– These design items are commonly known as the “assemblages”.
– Black box testing is used for exercising these assemblages through the interfaces.
– The simulation of the success and the error cases is done using the appropriate data inputs and the parameters.
– The simulation and the usage of the data areas of the shared is tested along with the inter – process communication.
– The exercising of the individual sub – systems is done via the input interface.
– The purpose behind the construction of the test cases is to test whether the individual components of the assemblages have proper interaction between them.
– The basic idea behind the integration testing is building block approach.
– The assemblages are verified and then added to the base that has already been verified.
– This hold set up is then used as a support for the integration testing of the other assemblages.
There are two types of integration testing namely:
However there are some other integration patterns available:
About Bottom – up Integration Testing
– In this approach to the integration, the first components to be tested are lowest – level components.
– These tested components are then used for facilitating the integration testing other higher level components.
– This process continues until the top most component of the system is tested.
– The low – level modules, functions and the procedures at the bottom are integrated prior to testing.
– After the lower – level integrated modules have been subjected to integration testing, the modules for the next level are integrated and are used for integration testing.
– Another point to be noted about the bottom – up testing is that it is useful only when almost all of the modules present at the same development level have successfully passed the integration testing.
– Further, this approach also helps in the determination of the software levels that are already developed and also makes it easy for the reporting the progress of testing in percentage.
– Here, the lower levels have to be tested extensively.
– This is required because only then it can be guaranteed that the highest module that is used is subjected to proper testing.
Following are some of the advantages of the bottom – up testing:
Following are the disadvantages of bottom – up type of integration testing:
The leftover modules that are also a part of the main program are taken one at a time and tested.