Long-Term Maintenance of Automated Test Suites: An Empirical Analysis

Abstract

Automated test suites are widely adopted to ensure software reliability. Over extended development cycles, however, test cases often lose effectiveness due to changing system behavior and requirements. This study investigates test case aging in eight open-source projects with development histories exceeding ten years. More than 420,000 test cases and 96,000 commits were analyzed. Results show that approximately 34% of test cases experienced declining fault detection rates after five years of maintenance. Factors such as API evolution, dependency upgrades, and configuration drift were identified as major contributors. A periodic test refactoring strategy was evaluated and reduced obsolete test cases by nearly 29%. The findings emphasize the importance of long-term test maintenance in large software ecosystems.