2.3 New

Approach to software development where every possible input from a user is considered

-to anticipate ways a user could misuse a program -ensure the final program is robust and reliable for all users

Ensure the software has a way of dealing with the potential errors to ensure software does not crash

-peripheral errors -disk errors -communication errors -division by 0

-When peripherals do not perform as intended -eg printer runs out of paper(fix is allow user to reprinting document after refilling the paper)

-Error that occur on a disk -such as disk running out of space(fix=allowing user to save work on another disk)

Applications using online systems losing online connection to the host server(fix = automatically retry if connection resumes)

Process of ensuring that a system is secure by asking the user to complete tasks to prove they are an authorised user of the system

-Usernames and passwords -CAPTCHA

Code which is used to check that an input from a user is acceptable and matches the requirements of the program

Length check Type check Range check Presence check Format check

Checking if what is entered is a certain data type such as integers for age

Ensuring data entered falls under a particular range such as between 0-100 for age

Checks the length of a string and checks if it meets the condition

Looks to check if any data has been entered in a field

Ensures that the data has been entered in the correct formate such as email containing @ and . symbol

Ensuring programmers can easily understand what a program is doing a long time after having written it

-commenting of code: explain the purpose of each code -white space(makes each section clear) -indentation: show each instance of selection and iteration and make it clear which doe belongs to which clause in the program -sensible variable names: name describes what the variable does to prevent confusion later on -use of sub programs: make reusable sections of code which removes the need for duplicating code and also structures the code better

-ensure there are no errors or bugs in the code -ensure that the code performs as it was intended -ensure no one can gain unauthorised access to the system -check the program solves in the initial problem and meets all requirements

Iterative testing Final testing

-each part of program is tested -every pathway through the program is tested(if statements) -done during development of program -make changes and improvements while testing

-Testing that all parts of a program work together -checking the program against real data to ensure it meets all of the requirements -testing program using normal, boundary and erroneous data -done towards end of development -can alpha testing or beta testing

-program will not execute when there is a syntax error (IDE provides information about the error)

-Program runs but expected output is not produced -check obvious areas such as logical and Boolean operators or division by 0