2.4.2 Impact Analysis for Maintenance

Impact analysis evaluates the changes that were made for a maintenance release to identify the intended consequences as well as expected and possible side effects of a change, and to identify the areas in the system that will be affected by the change. Impact analysis can also help to identify the impact of a change on existing tests. The side effects and affected areas in the system need to be tested for regressions, possibly after updating any existing tests affected by the change.

Impact analysis may be done before a change is made, to help decide if the change should be made, based on the potential consequences in other areas of the system.

Impact analysis can be difficult if:

• Specifications (e.g., business requirements, user stories, architecture) are out of date or missing

• Test cases are not documented or are out of date

• Bi-directional traceability between tests and the test basis has not been maintained

• Tool support is weak or non-existent

• The people involved do not have domain and/or system knowledge

• Insufficient attention has been paid to the software's maintainability during development