After new capabilities were deployed in a system, issues with preexisting capabilities were reported.

Unit testing is a testing technique that verifies the functionality and quality of individual units or components of software, such as modules, classes, functions, etc. Unit testing can help prevent issues with preexisting capabilities by detecting and fixing errors at an early stage of development, before they affect the integration and system testing. Unit testing can also ensure that new capabilities do not break or interfere with the existing ones, by checking the compatibility and dependencies of the units. Unit testing can be performed by developers using tools and frameworks that automate the process and generate reports. References = CompTIA Project+ PK0-005 Certification Study Guide, Chapter 10: Project Quality Management; CompTIA Project+ Certification Exam Objectives, Domain 3: Project Execution, Objective 3.2: Execute quality management activities.