debugging

Debugging failures systematically involves reproducing the bug, formulating a hypothesis, and bisecting commits to find the root cause. You write a failing reproduction test before changing code to verify the fix and prevent regressions.

To reproduce a bug, capture concise reproduction steps, environment details, and outputs to create a reliable failure. You then write a failing reproduction test that observes the failure before you attempt to fix the code.

Writing a failing test before fixing a bug enforces a disciplined workflow that validates the failure exists and confirms the fix works. This test-driven approach prevents future regressions by verifying the outcome.

Git bisect helps locate the root cause of a failure by systematically checking commits to identify the offending change. You use it after writing a failing reproduction test to isolate the exact commit that introduced the bug.

You need hypothesis-driven debugging when a user reports a bug or asks why something fails across a codebase. It involves iteratively testing likely causes to isolate the faulty component before writing a reproduction test.

This debugging workflow requires writing a failing reproduction test before changing code to observe the failure and verify the fix. Without running a test suite, you cannot systematically validate the outcome or prevent regressions.