[ISTQB] 2.4 Maintenance testing (K2)

According to ISTQB glossary, "maintenance testing is testing the changes to an operational system or the impact of a changed environment to an operational system"

LO-2.4.1 Compare maintenance testing (testing an existing system) to testing a new application with respect to test types, triggers for testing and amount of testing (K2) 

Maintenance testing is required when there are:
- new or modified requirements.
- migrations to an another platform.
- retirement of a function or a system needed to be replaced.

The aim is to ensure that existing system and functionalities are still correct and well incorporated in the existing operational system. The scope of maintenance testing is related to:

• the risk of the system being made.
• the extent of the changes being made.
• the size of the system changed.

These previous elements are used in impact analysis.

LO-2.4.2 Recognize indicators for maintenance testing (modification, migration and retirement) (K1) 

Change is necessary to answer to a business request or to maintain technology compatibility. 
Releases are then planned in advance and tested differently from hot fixes.

Maintenance testing may be carried out at any or all test levels and for any or all test types.
They require clear specification and knowledge as:

• Modifications to software are likely to be performed because of :
• planned enhancement changes or corrective patches needed for emergency changes.
• environment changes (OS/database upgrades).
• Migration includes operational tests upon new environment and software validation.
• Retirement includes testing data migration and data archiving.

LO-2.4.3 Describe the role of regression testing and impact analysis in maintenance (K2) 

According to ISTQB glossary "impact analysis is the assessment of change to the layers of development documentation, test documentation and components, in order to implement a given change to specified requirements".

Regression testing should be based on this impact analysis and be prepared beforehand.
It has to be systematically performed on the changed system and/or functionality when modifications, migrations, or retirement have been undertaken.