2.3 robust programs

• What is the main purpose of testing a program?

  To ensure that a program works correctly regardless of user input
• What are the key considerations for creating a secure and robust program?

  • Anticipating misuse
  • Input sanitisation
  • Validation
  • Verification
  • Authentication
  • Maintainable code
• Why is it important to test a program?

  To ensure user requirements are met, errors are removed, and the program doesn't crash
• What does anticipating misuse involve in defensive design?

  Planning ahead to take steps against potential misuse
• What are the two types of testing mentioned?

  • Iterative Testing
  • Final Testing
• What occurs during iterative testing?

  The programmer develops a module, tests it, and repeats until it works as expected
• What is input sanitisation in programming?

  Checking and cleaning up data that has been input
• What is final testing also known as?

  Terminal testing
• When does final testing take place?

  After development and before the program is released to the end user
• What is the purpose of validation in programming?

  To check whether input data follows specific criteria
• What is a syntax error?

  A mistake in the grammatical rules of the programming language
• What does verification check in a program?

  Whether data that has been entered is correct
• What happens when a syntax error occurs?

  The program cannot be compiled and executed
• What is authentication in the context of programming?

  Ensuring only authorised users can gain access to a system
• Give an example of a syntax error.

  Incorrect spelling: pront("hello")
• What does maintainable code allow other programmers to do?

  Read and quickly understand code that has been written
• What is a logical error?

  A mistake made by the programmer that causes incorrect output
• What are the types of validation checks mentioned in the study material?

  • Range Check
  • Type Check
  • Format Check
  • Presence Check
  • Lookup Table
  • Length Check
• What does a range check verify?

  That data is within a certain range
• What is the outcome of a logical error?

  The program runs without crashing but displays the wrong output
• What does a type check ensure?

  That data is a certain data type
• What is a format check used for?

  To ensure data is entered in a certain way
• Give an example of a logical error.

  Incorrect calculation: total = num1 - num2
• What does a presence check confirm?

  That data has actually been entered and not left blank
• What is test data used for?

  • To test whether a program is functioning correctly
  • Should cover a range of possible and incorrect inputs
  • Designed to prove a program works or highlight flaws
• What is a lookup table in programming?

  A table of acceptable entries, also known as a list
• What does a length check verify?

  That the length of the input is within a certain amount
• What are the four types of test data?

  1. Normal data - Sensible data the program should accept
  2. Boundary data - Data at the extreme boundary of data ranges
  3. Invalid data - Correct data type that does not meet validation rules
  4. Erroneous data - Wrong data type that the program cannot process
• What are the examples of making a program maintainable?

  • Using subprograms for code reuse
  • Appropriate variable names
  • Using indentation for readability
  • Adding comments for understanding
  • Using constants for consistency
• What is normal data in testing?

  Sensible data that the program should accept and process
• What is modularisation in programming?

  Using subprograms to reuse code and make it easier to test
• What is boundary data?

  Data at the extreme boundary of any data ranges
• Why are appropriate variable names important in programming?

  They ensure the purpose of a variable is immediately understood
• What is invalid data?

  Data of the correct type that does not meet validation rules
• How does indentation improve code readability?

  It clearly shows each ‘block’ of code
• What is erroneous data?

  Data of the wrong data type that the program cannot process
• What is the purpose of comments in code?

  To enable a programmer to understand the purpose of each line of code
• Why is using constants beneficial in programming?

  It keeps the program code consistent, making it easier to read and debug
• What are the questions related to Defensive Design in the study material?

  1. Describe the different considerations a programmer should make for a defensive design.
  2. Describe each validation check and give a suitable example.
  3. Explain the different ways a program can be maintained.