Developed a targeted testing enhancement for the facebook/jemalloc repository by implementing selective subtest execution controlled through an environment variable. Leveraging C programming and environment variable handling, the solution enables the test harness to read the JEMALLOC_TEST_NAME variable and execute only matching subtests within a test file. This approach streamlines debugging and accelerates continuous integration feedback by reducing the number of tests run per cycle. The feature, delivered as a single commit, improved resource utilization and testing determinism without introducing new bugs. The work demonstrated proficiency in testing frameworks, environment-driven feature flags, and integration with CI pipelines for efficient workflows.