PHPUnit Pocket Guide

Chapter 12. Other Uses for Tests

Once you get used to writing automated tests, you will likely discover more uses for tests. Here are some examples.

Agile Documentation

Typically, in a project that is developed using an agile process, such as Extreme Programming, the documentation cannot keep up with the frequent changes to the project's design and code. Extreme Programming demands collective code ownership, so all developers need to know how the entire system works. If you are disciplined enough to use "speaking names" for your tests that describe what a class should do, you can use PHPUnit's TestDox functionality to generate automated documentation for your project based on its tests. This documentation gives developers an overview of what each class of the project is supposed to do.

PHPUnit's TestDox functionality looks at a test class and all the test method names and converts them from camel case PHP names to sentences: testBalanceIsInitiallyZero( ) becomes "Balance is initially zero." If there are several test methods whose names differ only by a suffix of one or more digits, such as testBalanceCannotBecomeNegative( ) and testBalanceCannotBecomeNegative2( ), the sentence "Balance cannot become negative" will appear only once, assuming that all of these tests succeed.

The following code shows the agile documentation for the Bank Account class (in Example 10) generated by running phpunit --testdox-text BankAccountTest.txt BankAccountTest:

 BankAccount - Balance is initially zero ...