How Git Bisect Can Pinpoint a Buggy Commit in Just Four Test Runs

Git's built-in bisect tool uses binary search to identify which commit introduced a regression, requiring only a known good commit, a known bad commit, and a test that returns an exit code. In a 12-commit example repository, running 'git bisect run' with an automated test script narrowed down the culprit in just four steps without any manual intervention. The offending commit, labelled 'Perf: simplify addition loop', had stripped minus signs from numeric arguments, silently converting all negative numbers to positives. Git bisect works by checking out the midpoint of the commit range, running the test, and halving the search space based on the result — a process that scales logarithmically regardless of how many commits are involved. For reliable results, the test script must be independent of files added after the known-good commit, and endpoints must be verified, as an incorrect 'good' baseline will lead bisect to the wrong answer.