The framework used for tests is the SimpleTest unit tester.
The documentation for tests is quite explained and available at

Tests Folder

Every test should be included inside Tests folder.
The menu for test is automatically generated getting the name of the files inserted on it.
If a file starts with _, it will not be listed. This way, you can include files without displaying them.


Here is an example of test file:

//	ini_set('display_errors', 1);
//	error_reporting(E_ALL);

	SimpleTest::prefer(new TextReporter());
_MagratheaConfig.php file is:
class TestOfStaticConfig extends UnitTestCase{

	function setUp(){
	function tearDown(){

	// load a section in Static Config
	// I check if the section that it returns is an array:
	function testLoadSectionStaticConfig(){
		echo "testing magratheaConfig loading static config...";
		$thisSection = MagratheaConfig::Instance()->GetConfigSection("general");
		$this->assertIsA($thisSection, "array");

	// config file must have a default environment option
	function testConfigShouldHaveADefaultEnvironment(){
		echo "testing magratheaConfig confirming we have a default...";
		$env = MagratheaConfig::Instance()->GetEnvironment();

	// required fields
	function testConfigRequiredFields(){
		echo "testing magratheaConfig checking required fields...";
		$env = MagratheaConfig::Instance()->GetConfig("general/use_environment");
		$site_path = MagratheaConfig::Instance()->GetConfig($env."/site_path");
		$magrathea_path = MagratheaConfig::Instance()->GetConfig($env."/magrathea_path");
		$compress_js = MagratheaConfig::Instance()->GetConfig($env."/compress_js");
		$compress_css = MagratheaConfig::Instance()->GetConfig($env."/compress_css");

	function testReturnFalseWhenItemDoesNotExists(){
		echo "testing magratheaConfig should return false if item doesn't exists...";
		try {
			$thisIsFalse = MagratheaConfig::Instance()->GetFromDefault("idontexist");
			$this->fail("I should get an exception");
		} catch(Exception $e) {
			$this->assertEqual($e->getCode(), 704);
			$this->pass("exception ok!");


Keep testing...

It's a good programming practice to test your code.
For more information about testing and TDD, you can study Mauricio Aniche work: