Lab 05: Debug A Broken System

Practice debugging with evidence.

Use failure fixtures or take your ticket feature and intentionally add one bug:

• API returns wrong status code.
• Server accepts empty title.
• Database write fails.
• UI shows success even when API fails.
• Duplicate submit creates two tickets.

1. Write the expected behavior.
2. Reproduce the bug.
3. Capture logs or screenshots.
4. Identify the failing boundary.
5. Write a failing test.
6. Fix the root cause.
7. Run the test again.
8. Write a postmortem.

symptom
  -> where did the request enter?
  -> where did it change shape?
  -> where did it fail?
  -> what evidence proves that?

Create debugging-log.md with:

• Symptom.
• Reproduction steps.
• Evidence.
• Root cause.
• Fix.
• Verification.
• Prevention.

The postmortem names the root cause and includes proof that the fix works.