producing robust programs

producing robust programs

1. defensive design

   • maintainability
     • reduce the chance of introducing coding mistakes/bugs
       • comments
         • easy to read and understand
       • indentation
       • formatting
         • sub-routines
       • naming conventions
   • minimising/removing bugs
     • testing
       • iterative testing
         • testing should be ongoing through the development process
       • final testing
         • at the end of development, when the program is complete. makes sure it meets the requirements of the customer
       • making sure program functions as it was designed and meets the needs of the end user
       • 'alpha testing'
       • test plans
         • made up of:
           • reason for the test
           • the expected outcome
           • the actual result
         • test data
           • valid data
           • invalid data
           • borderline, on the edge between valid and invalid
   • validation
     • protection against unexpected user inputs
       • expect the unexpected
     • ensuring data entered is sensible and reasonable
       • type check
       • length check
       • format check
       • range check
       • presence check

2. authentication

   • check if the user is allowed access
     • making sure a person is who they say they are
   • usernames & passwords
     • passwords more secure, more complex
   • access rights
   • login attempts