Robust And Secure Programming
Overview
Ask a program for a number between 1 and 10 and somebody will type 0, and somebody else will type 11, and somebody else will type seven, and somebody else will press Enter without typing anything at all. None of those people is being difficult. They are what a user is, and a program that only works when it is given exactly what it expected is not finished.
This lesson covers the three things the specification asks for here. Writing simple data validation routines, using the checks it names by example: a minimum length, an empty string, and a number within a given range. Writing a simple authentication routine using a username and a password. And selecting suitable test data that covers normal, or typical, boundary and erroneous cases, and being able to justify the choice. That last objective is the one candidates prepare for least and it is worth as many marks as the other two.
Objectives
- Be able to write simple data validation routines.
- Be able to write simple authentication routines.
- Be able to select suitable test data that covers normal (typical), boundary and erroneous data. Be able to justify the choice of test data.
Mind map
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Robust And Secure Programming. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- Which of these is a data validation check named in the specification? A. Checking that a password has been encrypted B. Checking that a string is not empty C. Checking that a name is spelled correctly D. Checking that a user is over 18 by asking twice Answer: B
- A routine accepts values from 20 to 40 inclusive. Which is a boundary test value? A. 0 B. 30 C. 41 D. forty Answer: C
- Which loop structure is most appropriate for a validation routine? A. A FOR loop B. A REPEAT UNTIL loop C. A nested FOR loop D. No loop is needed Answer: B
- In an authentication routine, why should the failure message not say which of the username and the password was wrong? A. It would make the message too long B. It would confirm to a guesser that a username exists C. The program cannot tell which was wrong D. The specification forbids messages Answer: B
- What does validation check? A. That the data entered is true B. That the data entered is reasonable C. That the user is who they claim to be D. That the program has no syntax errors Answer: B
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