Test Data (SQA National 5 Computing Science): Revision Note

Suitable test data

What is suitable test data?

• Suitable test data is specially chosen to check that a program works correctly and produces the expected results in all situations

• During testing, the actual results are compared to the expected results to make sure the program behaves as intended

• Students must be able to describe, identify, exemplify, and implement the three main categories of test data:

  • Normal

  • Extreme

  • Exceptional

Example

• The following example checks if a user’s age is between 12 and 18

RECEIVE name FROM (STRING) KEYBOARD
RECEIVE age FROM (INTEGER) KEYBOARD

IF age >= 12 AND age <= 18 THEN
    SEND "Welcome " & name & ". Your age is accepted." TO DISPLAY
ELSE
    SEND "Sorry " & name & ". Your age is not accepted." TO DISPLAY
END IF

In Python, the same program would be:

name = input("What is your name? ")
age = int(input("How old are you? "))

if age >= 12 and age <= 18:
    print("Welcome,", name + "! Your age is accepted.")
else:
    print("Sorry,", name + ". Your age is not accepted.")

Normal test data

• Normal test data is data that should be accepted by the program

• It lies within the valid range and is of the correct data type

• Example:

  • Input → 16

  • Expected output → “Accepted”

Extreme test data

• Extreme test data is the lowest and highest values of valid data that should still be accepted by the program

• Example:

  • Input → 12 or 18

  • Expected output → “Accepted”

Exceptional test data

• Exceptional test data is data that is invalid and should be rejected by the program

• This could be the wrong data type, outside the valid range, or missing input

• Example:

  • Input → “F” or 11 or 19

  • Expected output → “Rejected”

Selecting suitable test data

• Using different categories of test data ensures that the program works correctly for valid inputs and handles invalid inputs without crashing