Stimulus: Sinema Aberlliw ticket bug report

Sinema Aberlliw, a small community cinema, wants a program that tells customers the price of a ticket.

Customer	Ticket price
Under 12	£5.50
65 and over	£6.00
Everyone else	£8.50

Customer

Ticket price

Under 12

£5.50

65 and over

£6.00

Everyone else

£8.50

2. Ifan’s program (Python)

1 age = int(input("Enter your age: ")) 2 if age < 12: 3 price = 5.50 4 elif age > 65: 5 price = 6.00 6 else: 7 price = 8.50 8 print("Your ticket costs £" + format(price, ".2f"))

3. Ifan’s test table (before the fix)

Test	Type	Input	Expected	Actual	Result
1	Typical	30	£8.50	£8.50	Pass
2	Boundary	11	£5.50	£5.50	Pass
3	Boundary	12	£8.50	£8.50	Pass
4	Boundary	65	£6.00	£8.50	Fail
5	Extreme	100	£6.00	£6.00	Pass
6	Erroneous	ten	A helpful message	Program stops with a ValueError	Fail

Test

Type

Input

Expected

Actual

Result

Typical

£8.50

Pass

Boundary

£5.50

Pass

Boundary

£8.50

Pass

Boundary

£6.00

£8.50

Fail

Extreme

100

£6.00

Pass

Erroneous

ten

A helpful message

Program stops with a ValueError

Fail

4. Ifan’s first draft of his test commentary

¹ When I tested the program it didnt work. ² Test 4 was wrong because their was a sintax error on line 4. ³ The program gave £8.50 to someone who was 65 and it should of been £6.00. ⁴ I changed the thing on line 4 to fix it. ⁵ I then tested it again and it works now. ⁶ Also when you type a word it crashs, I dont no why. ⁷ The progam is now finished and has no bugs.

(The small numbers show the sentence numbers. They are not part of Ifan’s writing.)

5. Useful technical words

Word	Meaning
syntax error	The code breaks the rules of the language, so it will not run at all, for example a missing colon.
logic error	The code runs, but gives the wrong result because the instructions are wrong.
runtime error	The program starts but stops while running, for example when int() is given a word.
condition	A test that is True or False, such as age > 65.
comparison operator	A symbol that compares two values: <, >, <=, >=, ==, !=.
boundary data	Values at the edge of a range, where mistakes are most likely.
validation	Checking that input is sensible before using it.
retest	Running the tests again after a change, including tests that passed before.

Word

Meaning

syntax error

The code breaks the rules of the language, so it will not run at all, for example a missing colon.

logic error

The code runs, but gives the wrong result because the instructions are wrong.

runtime error

The program starts but stops while running, for example when int() is given a word.

condition

A test that is True or False, such as age > 65.

comparison operator

A symbol that compares two values: <, >, <=, >=, ==, !=.

boundary data

Values at the edge of a range, where mistakes are most likely.

validation

Checking that input is sensible before using it.

retest

Running the tests again after a change, including tests that passed before.

6. What a good test commentary does

Says what went wrong: which test failed, the input, the expected and the actual result.

Explains why, using the correct technical terms.

Says exactly what was changed, and on which line.

Says how it was retested, with evidence.

Is honest about anything still not working.

Is accurate: correct spelling, punctuation and grammar, in a consistent tense.

Sinema Aberlliw: the ticket price bug and Ifan’s commentary

1. The brief

2. Ifan’s program (Python)

3. Ifan’s test table (before the fix)

4. Ifan’s first draft of his test commentary

5. Useful technical words

6. What a good test commentary does