Debugging Methodology

Reproduce, observe, hypothesize, isolate, verify. Resist guess-and-patch. Goal is root cause — fixing the wrong cause means it breaks again.

When to Use

• Test fails for non-obvious reason
• Behavior changed; cause unknown
• Bug is intermittent or environment-dependent
• User pattern-matches to a fix without root-cause evidence
• A fix was applied but the problem recurred or shifted

Core Methodology

Step 1: Reproduce the Failure