2.4.1 Impact analysis and regression testing
Usually maintenance testing will consist of two parts:
testing the changes
regression tests to show that the rest of the system has not been affected the maintenance work.
In addition to testing what has been changed, maintenance testing includes extensive regression testing to parts of the system that have not been changed. A major and important activity within maintenance testing is impact analysis. During impact analysis, together with stakeholders, a deci sion is made on what parts of the system may be unintentionally affected and therefore need careful regression testing. Risk analysis will help to where to focus regression testing it is unlikely that the team will have time to repeat all the existing tests. If the test specifications from the original development of the system are kept, one may be able to reuse them for regression testing and to adapt them for changes to the system. This may be as simple as changing the expected results for your existing tests. Sometimes additional tests may need to be built. Extension or enhancement to the system may mean new areas have been spec ified and tests would be drawn up just as for the development. It is also possible that updates are needed to an automated test sct. which is often used to support regression testing.