Modern software development requires constant code evolution, often leading to a misalignment between evolving source code and its associated test suite. This lack of synchronization can impact software quality and longevity. This research investigates the factors influencing test co-evolution and its impact on software development practices. Our methodology involved analyzing the evolution of test code proportions, employing clustering techniques to identify distinct evolution patterns, and classifying projects based on their level of test co-evolution using the Pearson Correlation Coefficient. Our findings revealed five distinct test evolution patterns, highlighting diverse approaches to integrating testing within development workflows. Furthermore, high test co-evolution correlated significantly with smaller development teams and a lower frequency of corrective and multi-maintenance activities, indicating a potential link between consistent test updates, early defect detection, and improved code quality.