Worked example: Redrafting a Test Commentary for a Bug Fix

What this is

A complete, secure Year 11 answer, annotated so you can see which success criterion each part meets. It is also the answer key. The bug: line 4 uses age > 65, so a 65-year-old pays £8.50; it should be age >= 65. This is a logic error, not a syntax error, because the program runs. The most common weaknesses in redrafts are keeping “it works now” without evidence, and keeping the untrue claim that the program “has no bugs”.

Step 1: understand the bug

Age	11	12	64	65	66
Price given	£5.50	£8.50	£8.50	£8.50	£6.00
Correct?	Yes	Yes	Yes	No, should be £6.00	Yes

(b) Line 4, elif age > 65:, should be elif age >= 65:, because the brief says “65 and over”.

Step 2: proofread

Ifan wrote	Code	Correction
didnt (sentence 1)	P	didn’t (apostrophe for the missing o)
it didnt work (1)	V	Test 4 failed: the program gave the wrong price for age 65.
their was (2)	Sp	there was
sintax error (2)	Sp and T	Spelled syntax, but the right term is logic error: the program ran.
should of been (3)	G	should have been
the thing on line 4 (4)	V	the comparison operator > in the condition on line 4
tested it again and it works now (5)	E and G	Which tests, with what results? Tense changes from past to present.
crashs (6)	Sp	crashes
it crashs, I dont no why (6)	P and Sp	Comma splice: use a full stop. don’t know. Also name it: a runtime error (ValueError).
progam (7)	Sp	program
has no bugs (7)	H	Not true: test 6 still fails.

The pupil works sentence by sentence and finds more than 10 problems, and separates surface errors (spelling, punctuation) from deeper ones (wrong term, no evidence, untrue claim). Evidences criteria 1, 2 and 4.

Step 3: precise terms

Ifan wrote	Precise version
it didnt work	Test 4 (boundary data, age 65) failed.
a sintax error on line 4	a logic error in the condition on line 4
I changed the thing on line 4	I changed the comparison operator on line 4 from > to >=
it works now	tests 1 to 5 now pass
when you type a word it crashs	entering a word causes a runtime error (ValueError), because int() cannot convert text such as “ten” to a number

Step 4: fix the structure

Part	Sentences	What is missing
What went wrong and why	1, 2, 3	The expected and actual result in one place; the correct type of error; why > excludes 65.
What I changed	4	The exact change: > to >=.
How I retested, and what still needs work	5, 6, 7	Which tests were rerun and their results; an honest note that test 6 still fails.

Step 5: redraft (model, 144 words)

What went wrong. Test 4 used boundary data: an age of 65. The brief says customers aged 65 and over pay £6.00, but the program output £8.50. This was a logic error, not a syntax error, because the program ran without stopping. The condition on line 4, age > 65, is only True for ages above 65, so a customer aged exactly 65 fell through to the else branch.

What I changed. I changed the comparison operator on line 4 from > to >=, so the condition became age >= 65.

How I retested. I reran all six tests. Test 4 now outputs £6.00 as expected, and tests 1, 2, 3 and 5 still pass. However, test 6 still fails: entering “ten” causes a runtime error (ValueError) because int() cannot convert text. The program therefore needs input validation before it is finished.

The three parts answer what went wrong, what changed and how it was retested. Every claim has evidence, the technical terms are correct, and the final paragraph is honest about test 6. The past tense is used for actions and the present tense for what the code does now. Evidences criteria 1 to 4.

Step 6: feedback and response (model)

Partner’s comment: “Your first paragraph says the result was wrong but not what price it gave. Add the actual output.”

Response: “I added ‘but the program output £8.50’, so the reader can compare the expected and the actual result without looking at the table.”

The response names the exact change and why it helps the reader. Evidences criterion 5.

If you finish early: answers

For example, replace line 1 with:

text = input("Enter your age: ") while not text.isdigit(): text = input("Please enter your age in digits: ") age = int(text)

This keeps asking until the input is made only of digits, so int() never receives a word.
Age 64: expected £8.50. Age 66: expected £6.00. (Testing either side of 65 shows the boundary is in exactly the right place.)
A change to one line can accidentally break something that worked before, so all the tests must be rerun to show nothing else has changed.

Why this response is secure

Proofreading is systematic and every error is corrected.
Vague words and the wrong error type are replaced with precise terms.
The redraft is organised into what went wrong, what changed and how it was retested.
Evidence is added and the untrue claim is removed.
Feedback leads to a specific, explained improvement.