Producing robust programs (defensive design)

Producing robust programs (defensive design)

1. produce - to make

2. robust - won't break

3. defensive design - helps make the program more robust

   • protection against unexpected user inputs
     • e.g. numbers or emojis instead of letters
     • Validation and validation checks
       • sensible and reasonable
       • e.g. type, length, format, range check
         • letters only
         • min 1 length
         • max 2 length
         • pattern
   • maintainability
     • reducing the chance of introducing coding mistakes/bugs
       • adding comments
         • pinpoint errors and explain what each line should be doing
       • indentation
       • formatting
         • clear and less likely to make a mistake, easier to read
   • minimising/removing bugs

4. Testing

   • a program functions as it was designed and meets the need of the user
   • iterative testing
     • final testing
       • tested as a whole
     • repeated testing

5. valid, invalid, borderline data

6. authentication

   • have to have usernames/passwords
   • access rights