What is the entry and exit criterion for integration testing?

Integration testing as we know is the second main software testing methodology in the software testing life cycle or STLC after unit testing. It is succeeded by the system testing and system integration testing substantially.

Like for every other testing methodology, a software system or application can undergo testing only after passing some pre- defined entry criteria and for exiting the testing phase also it needs to pass some pre- defined exit criteria in integration.

This article is focussed up on the entry and exit criterion for the integration testing. But, let us brief up ourselves with the concepts of integration testing so that it becomes easy for us to define with the entry and exit criteria defined for integration testing.

About Integration Testing

- Integration testing is sometimes abbreviated as I & T i.e., integration and testing.

- Integration testing has been named so because it involves the integration of the software system or application modules before carrying out the testing on them.

- Thus, we can say that the it is contrary to the unit testing since here it involves the testing of the system modules as groups of two or more modules rather than carrying out testing on them as individual modules like in the case of unit testing.

- Integration testing is often carried out after the unit testing but before the validation testing.

- Only those individual system modules which have passed the unit testing with successful grades can be considered as a valid input for the test cases created for the integration testing.

- Though, in some cases there might be some exception if error present in any individual module can only be rectified in the later stages of the testing cycle.

- When the groups or aggregates of the modules pass the integration testing, then only they can be moved further for the system testing and system integration testing.

- The reliability requirements, performance requirements and the functional requirements that have been specified for the major design items are what are tested by the integration testing.

- By major design items, here we mean the group of units or modules or assemblages.

- These assemblages or groups of units are put together via their interfaces by implementing the black box testing techniques and the faults and errors are simulated according to the proper defined parameters and the input data values.

- The inter process communication occurring as a result of the integration between the several unit groups is also tested apart from just testing the above mentioned requirements.

- The implementation of these small sub systems takes place through the interface of the input.

- A verified base is prepared on which the various assemblages are placed which is then used as a support to the integration testing test cases for the testing of the other assemblages.

- This approach has been termed as the “building block approach”. Integration testing can be implemented via any of the below mentioned approaches:
1. Big bang approach
2. Usage model testing
3. Top down approach
4. Bottom up approach
5. Sandwich testing

Entry criteria for Integration testing

- The system units or modules needed for the integration must be ready to be integrated.
- Unit testing must have been completed and closed.
- All the issues discovered during the unit testing must have been addressed and closed.
- The test scripts for the integration testing should be ready.
- The testing should be commenced as per the schedule and the plan.
- The test environment should be ready.

Exit criteria for Integration testing

- Issues discovered during the integration testing must be addressed, fixed and closed..
- 10 percent of the benchmark as decided by the QA people is supposed to be allowed for the issues that outstand.
- All the test cases must be executed and passed.
- Transition meeting should be signed off.