SAM HARRIS TECH REVISION

OCR GCSE CS - 2.3 Producing Robust Programs

2.3 Producing Robust Programs (OCR J277)

Anticipating Misuse: Thinking about how a user might break the program and preventing it.
Authentication: Confirming the identity of a user (e.g., passwords, biometrics) before allowing access.
Input Validation: Checking if data is sensible before processing (e.g., Range check, Type check, Length check, Presence check, Format check).
Maintainability: Writing code that is easy for others to understand and update using:
- Comments (# or //) to explain logic.
- Indentation to show code structure.
- Meaningful variable names (e.g., "score" instead of "s").
- Constants for values that don't change.
- Subprograms (functions/procedures) to avoid repetition.

Purpose of Testing: To ensure the program works as expected and to find/fix logic and syntax errors.
Iterative Testing: Testing modules of code as they are being developed.
Final/Terminal Testing: Testing the complete program after development is finished.
Test Data:
- Normal: Data the program should accept (e.g., 5 for a 1-10 range).
- Boundary: Data at the very edge of the limit (e.g., 1 or 10).
- Invalid: Data of the right type but outside the range (e.g., 15).
- Erroneous: Data of the wrong type (e.g., "hello" instead of a number).