Before performing a test, you need to decide what data you are going to include in your test case. It is not normally possible to perform tests with every single possible piece of data. So, instead the developers will choose from a limited range of data such as:
- valid - the most obvious or common data that should work
- valid extreme - unusual, extreme or unexpected data, eg the highest and lowest (data that tests the limits but that should work)
- invalid - data that should definitely fail
- invalid extreme - data that is at the edge of failure and is nearly acceptable
- erroneous - data that is the wrong data type
Tests should find that the program works as expected. Obvious input data should confirm that the software works as expected. Extreme test data will be chosen to test what breaks the system.
For example, if you were developing a number-guessing game, you might have a unit of code that asks the user to choose a number in a specific range, eg "Choose a number between 1 and 10". To test this unit, you could try a whole range of inputs to see what happens:
3, 4.5, three, -99, 10.00001
GCSE coursework for Computer Science will not count for any marks amid fears about widespread cheating, the exam watchdog has said.
The move follows concern that thousands of students were given undue assistance, with Ofqual finding dozens of examples where students were able to obtain answers posted on online forums and websites.
Examples of malpractice included students posting the tasks on forums asking for help, with other members responding with detailed solutions and code which they could simply copy and past.
The watchdog has now ruled that coursework - which is meant to make up 20 per cent of a student’s overall grade - will not count towards the final grade for all Computer Science students sitting their exams in 2018 and 2019.
“The speed with which the tasks appeared on-line and the number of times the discussions and solutions were viewed threatened the integrity of this aspect of the qualification,” Ofqual’s report said.
In November, the exams watchdog launched a consultation on changes to computer science.
Yesterday, their report said that responses to the consultation confirmed their view that the “current situation is untenable”.