Fiducia TogetherTesting and debugging
Checking a program works, and finding out why it does not.
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.
What it is
Testing checks a program against its requirements. Test data comes in three kinds: normal, boundary and erroneous. A syntax error breaks the rules of the language; a logic error runs and gives the wrong answer.
Where it applies
GCSE and A Level computer science, and it is directly assessed.
How it works
Boundary testing catches the commonest class of bug: the value at the edge of a valid range, where off-by-one errors live.
A logic error is harder to find than a syntax error precisely because nothing complains.
How to use it in your work
Produce a test plan as a table: test, data, expected result, actual result. That table is the answer to most testing questions.
Always include boundary and erroneous data. Testing only normal data is the standard lost mark.
For debugging, use a trace table — it is the technique the exam expects.
Where to get help
Your teacher and your board's specification and mark scheme.
Revise this with a song
These are ours. We write revision songs because a lot of people remember a tune when they cannot remember a page, and because revising out loud in the kitchen beats staring at a highlighter.
- The Computer Science Song The GCSE computer science topics, set to music.
Where to read more
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.