System Integration testing:

• The objective of system integration is to build a “working” version of the system by (i)putting the modules together in an incremental manner and (ii) ensuring that the additional modules work as expected without disturbing the functionalities of the modules put together.

• Integration testing provides a systematic technique for assembling a software system while conducting tests to uncover errors associated with interfacing.

• The application is tested in order to verify that it meets the standards set by the client as well as reassuring the development team that assumptions which were made during unit testing are correct.

• Integration testing need not wait until all the modules of a system are coded and unit tested. Instead, it can begin as soon as the relevant modules are available.

• Integration testing or incremental testing is necessary to verify whether the software modules work in unity.

• System Integration testing includes a number of techniques like Incremental, Top- down, Bottom –Up, Sandwich and Big Bang Integration techniques.

Test Plan for System Integration Testing (SIT) :

• System integration testing requires a controlled execution environment, much communication between the developers and the test engineers which is handled with much planning in the form of developing a SIT Plan.

• A useful framework for preparing an SIT Plan is outlined as follows :

  1.Scope of testing

  2.Structure of integration levels

  • Integration test phases

  • Modules or subsystems to be integrated in each phase

  • Building process and schedule in each phase

  • Environment to be set up and resources required in each phase

  3.Criteria for each integration test phase n

  • Entry criteria

  • Exit criteria

  • Integration techniques to be used

  • Test configuration set up

  4.Test specification for each integration test phase

  • Test case ID number

  • Input data

  • Initial condition

  • Expected results

  • Test procedure

How to execute this test?

How to capture and interpret the results ?

1. Actual test results for each integration test phase

2. References

3. Appendix

In the scope of testing section, one summarizes the system architecture. Specifically, the focus is on the functional, internal and performance characteristics to be tested. System integration methods and assumptions are included in this section.

• The next section, structure of integration levels, contains four subsections.

• The first subsection explains the division of integration testing into different phases, such as functional, end-to-end and endurance phases.

• The second subsection describes the modules to be integrated in each of the integration phases.

• The third subsection describes the build process to be followed: daily build, weekly build, biweekly build or a combination thereof.

• A schedule for system integration testing is given in the third subsection. Specifically one identifies the start and phase of testing.

• In the fourth subsection, the test environment and the resources required are described for each integration phase. The hardware configuration, emulators, software simulators, special test tools, debuggers are testing techniques are discussed in the fourth subsection.

• The start date and the stop dates for a phase are specified in terms of entry criteria and exit criteria, respectively.

• Test specification section describes the test procedure to be followed in each integration phase. The detailed test cases, including the input and expected outcome for each case, are documented in the test specification section.

• The history of the actual test results is recorded in the fifth section of the SIT plan.

• Finally references and appendix, if any are included in the test plan.