Testing: test data, test plans, errors – GCSE Computer Science exam questions with mark scheme

1Grade 4–54 marks

A program accepts a whole number from 1 to 100 inclusive.

Give an example of each type of test data for this program.

(a) Normal [1] (b) Boundary [1] (c) Invalid [1] (d) Erroneous [1]

(a) Any whole number from 2 to 99, e.g. 50 (1 and 100 are boundary data)(1)
(b) 1 or 100; do not accept 0 or 101 (J277 defines boundary data as the correct type at the edge of what is valid, so 0 and 101 are invalid data)(1)
(c) A whole number outside the range, e.g. 0, 101, 150 or −5; do not accept a decimal or text (wrong data type = erroneous)(1)
(d) Data of the wrong type, e.g. "ten" / a letter / 4.5 (not a whole number)(1)
Answer: (a) 50; (b) 100; (c) 150; (d) "ten"
Examiner tip: Invalid data is the right type but outside the range. Erroneous data is the wrong type altogether. Don't swap them.

2Grade 4–54 marks

(a) Describe what is meant by iterative testing. [2]

(b) Describe what is meant by final (terminal) testing. [2]

(a) Testing is carried out during development(1)
(a) Each module / section is tested, fixed and retested repeatedly as it is written(1)
(b) Testing is carried out at the end of development(1)
(b) The whole program is tested to check it meets the requirements / works as a complete system(1)
Answer: (a) Repeated testing of each part during development; (b) testing the whole program at the end against the requirements
Examiner tip: Say WHEN each kind of testing happens and WHAT is tested. You need both for the two marks.

3Grade 6–75 marks

This program should output the average of 5 numbers.

01 total = 0
02 for i = 1 to 5
03     num = int(input("Enter number"))
04     total = total + num
05 next i
06 average = total / 4
07 print("Average is " + str(average)

(a) State what is meant by a syntax error. [1]

(b) Identify the line number of the logic error and write the corrected line. [2]

(a) An error that breaks the grammatical rules of the programming language, so the program cannot be translated / run; do not accept 'a spelling mistake' alone(1)
(b) Line 06(1)
(b) average = total / 5(1)
(c) Line 07(1)
(c) print("Average is " + str(average)) – closing bracket added(1)
Answer: (a) An error that breaks the rules (grammar) of the language; (b) line 06 → average = total / 5; (c) line 07 → print("Average is " + str(average))
Examiner tip: A logic error still runs but gives the wrong result, so line 06 is a logic error, not a syntax error.

Still losing marks on this topic?

Book a free introductory session and we'll find exactly which step is costing you.

Book a free intro