The Book of Ruby

Unit Testing

Unit testing is a postdebugging testing technique that lets you try bits of your program in order to verify that they work as expected. Some programmers use unit testing habitually in addition to or even instead of interactive debugging; other programmers use it rarely or never. Entire books have been written on the techniques and methodologies of unit testing, and I will only cover its fundamentals here.

The basic idea of unit testing is that you can write a number of “assertions” stating that certain results should be obtained as the consequence of certain actions. For example, you might assert that the return value of a specific method should be 100, that it should be a Boolean, or that it should be an instance of a specific class. ...