Suitable Test Data (Cambridge International IGCSE Computer Science)

Spec point — 6.3.6 · 6 Suggest and apply suitable test data

Suitable Test Data

What is suitable test data?

• Suitable test data is specially chosen to test the functionality of a program or design

• Developers or test-users would pick a selection of test data from the following categories

  • Normal
  • Abnormal
  • Extreme
  • Boundary

• The results would be compared to the expected results to check if the algorithm/program works as intended

• Each category is explained within the context of a simple Python program below, comments have been added to help explain the processes

Normal data

• Normal test data is data that should be accepted in the program
• An example would be a user entering their age as 16 into the age field of the program

Abnormal data

• Abnormal test data is data that is the wrong data type
• An example would be a user entering their age as "F" into the age field of the program

Extreme data

• Extreme test data is the maximum and minimum values of normal data that are accepted by the system
• An example would be a user entering their age as 18 or 12 into the age field of the program

Boundary data

• Boundary test data is similar to extreme data except that the values on either side of the maximum and minimum values are tested
• The largest and smallest acceptable value is tested as well as the largest and smallest unacceptable value
• An example would be a user entering their age as 11 or 19 into the age field of the program

Selecting suitable test data

Worked Example A programmer has written an algorithm to check that prices are less than $10.00

These values are used as test data: 10.00 9.99 ten

State why each value was chosen as test data.

[3]

Answers

Final answer: 10.00 is boundary or abnormal data and should be rejected as it is out of range [1]

Final answer: 9.99 is boundary, extreme and normal data and should be accepted as it is within the normal range [1]

Final answer: Ten is abnormal data and should be rejected as it is the wrong value type [1]