PHPUnit - 'No tests executed' when using configuration file

The Problem

To improve my quality of code, I've decided to try to learn how to test my code using Unit Testing instead of my mediocre-at-best testing solutions.

I decided to install PHPUnit using composer for a personal library that allows me to achieve common database functions. At first I didn't have a configuration file for PHPUnit and when I ran commands like:

phpunit tests/GeneralStringFunctions/GeneralStringFunctionsTest

The output is what I expected:

Time: 31 ms, Memory: 2.75Mb
OK (1 test, 1 assertion)

I then tried to use a configuration file to automatically load the testsuite instead of having to manually type in the file every time. I created a file called phpunit.xml in my root directory, and entered the following into the file: http://ift.tt/193wSk7.

Now, when I run the command:

phpunit

I get the following output:

PHPUnit 4.5.0 by Sebastian Bergmann and contributors.

Configuration read from /Users/muyiwa/Projects/DatabaseHelper/phpunit.xml



Time: 16 ms, Memory: 1.50Mb

No tests executed!

In case it's helpful, my directory structure is as follows:

src - Top level directory (with all my source code)

tests - Top level directory (with all my tests, structured the same as my src folder)

vendor - Composer third party files

I also have the composer json and lock file, as well as the phpunit xml file in the top level as files.

Things I've Tried

• Changing the directory in phpunit.xml to tests/GeneralStringFunctions


• Adding a suffix attribute to the directory tag in phpunit.xml to specify "Tests" as the explicit suffix.