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INTEGRATION AND SYSTEM TESTING

The third stage of the production process is to integrate major components resulting from coding and unit testing into the system. In the fourth stage of production, the fully integrated system is tested.

Integration

Integration is the process of building a software system by combining components into a working entity. Integration of components should proceed in an orderly function-by-function sequence. This allows the operational capabilities of the software to be demonstrated early, and thus gives visible evidence that the project is progressing.

Normally, the first components to be integrated support input and output. Once these components have been integrated and tested, they can be used to test others. Whatever sequence of functions is used, it should minimise the resources required for testing (e.g. testing effort and test tools), while ensuring that all source statements are verified. The Software Verification and Validation Plan section for the integration tests (SWP/IT) should define the assembly sequence for integration.

 

ESAPSS-05-05 Issue 1 (May 1992) 21 THE DETAILED DESIGN AND PRODUCTION PHASE

Within the functional groupings, components may be integrated and tested top-down or bottom-up. In top-down integration, 'stubs' simulate lower-level modules. In bottom-up integration, 'drivers' simulate the higher-level modules. Stubs and drivers can be used to implement test cases, not just enable the software to be linked and loaded.

The integration process must be controlled by the software configuration management procedures defined in the SCMP (DD05). Good SCM procedures are essential for correct integration. All deliverable code must be identified in a configuration item list (DD12).

Integration testing

Integration testing is done in the DD phase when the major components defined in the ADD are assembled. Integration tests should verify that major components interface correctly.

Integration testing must check that all the data exchanged across an interface comply with the data structure specifications in the ADD (DD07). Integration testing must confirm that the control flows defined in the ADD have been implemented (DD08).

Integration test designs, test cases, test procedures and test reports are documented in the Integration Test section of the Software Verification and Validation Plan (SWP/IT).

System testing

System testing is the process of testing an integrated software system. This testing can be done in the development or target environment, or a combination of the two. System testing must verify compliance with system objectives, as stated in the SRD (DD09). System testing should include such activities as:

• passing data into the system, correctly processing and outputting it (i.e. end-to-end system tests):

• practice for acceptance tests (i.e. verification that user requirements will be met);

• stress tests (i.e. measurement of performance limits);



• preliminary estimation of reliability and maintainability:

• verification of the Software User Manual.

 

22 ESAPSS-05-05 Issue 1 (May 1992) THE DETAILED DESIGN AND PRODUCTION PHASE

Trends in the occurrence of defects should be monitored in system tests; the behaviour of such trends is important for the estimation of potential acceptability.

For most embedded systems, as well as systems using special peripherals, it is often useful or necessary to build simulators for the systems with which the software will interface. Such simulators are often required because of:

• late availability of the other systems:

• limited test time with the other systems:

• desire to avoid damaging delicate and/or expensive systems.

Simulators are normally a separate project in themselves. They should be available on time, and certified as identical, from an interface point of view, with the systems they simulate.

System test designs, test cases, test procedures and test reports are documented in the System Test section of the Software Verification and Validation Plan (SVVP/ST).

The SUM is a key document during system (and acceptance) testing. The developers should verify it when testing the system.


Date: 2016-01-03; view: 765


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