Testing and Debugging

Selecting Test Cases

Positive tests consist of legitimate inputs that you expect the program handles correctly.
Boundary cases are also legitimate inputs that you expect the program to handle in a trivial way.
Negative cases are inputs that you expect the program to fail on.
Keeping test data in a file is smart because you can use it to review every version of the program.
When you find a bug, you should record the data that caused the bug, and retest your program with that data after you have tried to fix the bug.
The phenomenon of fixing a bug, only to have it reappear after further program modifications is called cycling.
The process of testing against a set of past failures is called regression testing.