2.3 - Robust Programs

2.3 - Robust Programs

1. Keywords

   • Data Validation
     • Ensures data is valid - within limits or parameters. NOT neceessarily the correct answer.
   • Data Sanitisation
     • Cleaning up data.
   • Authentification
     • A coding method checking that a user is who they claim to be.
   • Maintainability
     • To protect against attacks, computers must be maintained and kept up to data.
   • Comments
     • Informs a reader of a bug or issue.
     • Used to explain code and its' function in more detail.
     • Stops a line or section of code from executing.
   • Indentation
     • Used to group a function, doesn't use a { syntax as this is used instead and it is easier to see issues when altering a program.
   • Iterative testing
     • Testing as you go along.
   • Final/Terminal Testing
     • Testing at the end.
   • Syntax errors
     • Mistakes in the way the code is written.
   • Logic errors
     • A bug that still allows a program to run but incorrectly. NOT always obvious.
   • Test data
     • Valid, normal/real, eroneous, extreme, null, invalid.
   • Data Verification
     • Makes data correct through double-checking or proof-reading.

2. Defensive Design Considerations

   • Make a list of where you commonly enter data.
   • When data is entered into a program, it is important that it is valid in order for program to operate correctly.
     • Garbage In Garbage Out
   • Sometimes, users will deliberately enter incorrect data to access program/data.

3. Validation

   • Length Checks, check digit, format check, lookup data, presence check, range check or spell check.

4. Input Sanitisation

   • Strips strings, removing uwanted characters. Ensuring input is correct and contains only permitted characters.

5. Anticipating Misuse

   • Considers and anticipates misuse like a brute force attack on the program.
   • An example would be only allowing one vote per person.
   • Planning for contingencies
     • Planning for an issue that occurs due to anticipating the misuse. An example would be limiting the number of login attempts.
     • Or use authentification.

6. Authentification

   • A coding method to check that a user is who they claim to be and are allowed to access the program.
   • Can be physical, new software tends to require key codes, methods include passwords to image scanners, also occurs when you access a website as you request access to the ssrver.

7. Maintainability

   • API and code changes lead to programs needing to adapt and complement new requirements using comments and indentations.

8. Error

   • AKA bug,
   • Something that makes a program run incorrectly.

9. Runtime Errors

   • Only detected when running and nothing is wrong with the code.
   • An example would be memory running out.

10. Syntax Errors

    • Mistakes in the way the code is written like spelling mistakes.

11. Logic Errors

    • NOT always recognised.

12. Iterative Testing

    • Similar to a guitar ~ tweak, tweak, tweak.

13. Final/Terminal Testing

    • Checks what happens when a range of pre-defined test data is entered/used in the program.

14. Test Plans

    • Should be set out: test number, data entered, type of test data, expected outcome, result of the test, action required as a result.