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Tuesday, September 28, 2010

Different testing activities in Programming/Construction and Operations and Maintenance Phase

The main testing points in this phase are:
- Check the code for consistency with design
The areas to check include modular structure, module interfaces, data structures, functions, algorithms and I/O handling.

- Perform the testing process in an organized and systematic manner with test runs dated, annotated and saved.
A plan or schedule can be used as a checklist to help the programmer organize testing efforts. If errors are found and changes are made to the program, all tests involving the erroneous segment must be re-run and recorded.

- Asks some challenges for assistance
Some independent party, other than the programmer of the specific part of the code should analyze the development product at each phase. The programmer should explain the product to the party who will then question the logic and search for errors with a checklist to guide the search. This is needed to locate errors the programmer has overlooked.

- Use available tools
The programmer should be familiar with various compilers and interpreters available on the system for the implementation language being used because they differ in their error analysis and code generation capabilities.

- Apply stress to the program
Testing should exercise and stress the program structure, the data structures, the internal functions and the externally visible functions or functionality. Both valid and invalid data should be included in the test set.

- Test one at a time
Pieces of code, individual modules and small collections of modules should be exercised separately before they are integrated into the total program, one by one. Errors are easier to isolate when the number of potential interactions should be kept small. Instrumentation-insertion of the some code into the program solely to measure various program characteristics can be useful here.

- Measure testing coverage/ When should testing stop?
If errors are still found every time the program is executed, testing should continue. Because errors tend to cluster, modules appearing particularly error-prone require special scrutiny. The metrics used to measure testing thoroughness include statement testing, branch testing and path testing. Statement testing is the coverage metric most frequently used as it is relatively simple to implement.

Testing Activities in Operations and Maintenance Phase

Correctness, modifications and extensions are bound to occur even for small programs and testing is required every time there is a change. Testing during maintenance is termed regression testing. The test set, test plan, and the test results for the original program should exist. Modifications must be made to accommodate the program changes, and then all portions of the program affected by the modifications must be re-tested. After regression testing is complete, the program and test documentation must be updated to reflect the changes.

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