Reduce problems to evidence and repeatable tests
Goal
You should be able to demonstrate the result described in the lesson and explain why each step was necessary.
You should be able to demonstrate the result described in the lesson and explain why each step was necessary.
Step-by-step
01
Reproduce the failure
Write down exact inputs and steps.
02
Read the first error
The earliest useful error often explains later cascading failures.
03
Narrow the scope
Commenting out random code is less useful than isolating one boundary at a time.
04
Inspect values
Log or print the values entering and leaving the suspicious step.
05
Change one thing
Make one change, rerun the same test, and record the result.
Verify before moving on
You should be able to demonstrate the result described in the lesson and explain why each step was necessary.
You should be able to demonstrate the result described in the lesson and explain why each step was necessary.
Troubleshooting
If a command or screen differs from the lesson, stop and verify the version you are using before forcing a change.
What you learned
You now understand the purpose of this part of the system and have a concrete result you can verify before continuing to the next lesson.