Test data

Max = 0
FOR i <- 0 to 10
  INPUT Number
  IF Number > Max THEN
    Max <- Number
  END IF
Next i
PRINT Max

Read the following Python code:

1. What is this program doing?
2. How can you sure this program is functioning correctly?

Test data

• We need to test a program to see whether it works or not
• We need to prepare sets of test data and feed into the program
• If all the outputs of the program is the same as our expected output then the program is good

Types of test data

*Assume we have a program that collects 3 exam scores and calculate the average

Test plan

*Assume we have a program that collects 3 exam scores and calculate the average

Test plan

• A good plan is always important before you do a program
• Include test data from different types
• Fill in the expected output before creating your solution
• After the program is created, fill in the actual outcome and if the actual outcome is different from expected, the Action
• Any changes to the program should re-run the test

Trace table

• A table used to trace the values of variables
• Often use with dry-run
• Helps to determine where are the errors in the code

Specimen paper 2015

Always prompt the user about what's happening!

Verification

• Prevent errors when data is copied from one place to another (e.g. typing)
• Data can be totally valid, but it is incorrect

Validation

• Check the data if it satisfies criteria required by system
• Usually done automatically by the software

Think Pair Share

Imagine you are required to input some data in an online application form. Discuss and suggest some verification methods

Verification methods

• Visual check or proof reading
• Double entry

Validation types

Please input the score: 120
Input must between 0 and 100
Please input the score: Fifty-one
Input must be an integer
Please input the score: 85

Common validation pattern

• Program should do the validation check, and reject any invalid inputs
• Only accepts when the input is valid

Check digit

• (Usually) final digit included in a code
• Calculated from other digits in the code
• Prevents errors from entering numbers
  • From Human entry
  • For Input devices (e.g. Barcode scanner)
• Some examples are:
  • ISBN number
  • Your DESJ Number
  • ID Card number

Research

• There are 2 versions in ISBN (What is ISBN?) which are:
  • ISBN 10
  • ISBN 13
• Research and find the formula for calculating the ISBN-13 check digit (p.123 in textbook)

Class exercise

• Create a program (Validations) to ask user to input:
  • Student name
  • Student gender ('m' or 'f')
  • Student score
• All inputs must be validated
• Must properly prompt user for input and expectations
• Print the entered data