silverstripe-environmentcheck/code/checks/HasClassCheck.php

<?php

/**
 * Check that the given class exists.
 */
class HasClassCheck implements EnvironmentCheck {
	/**
	 * @var string
	 */
	protected $className;

	/**
	 * @param string $className The name of the class to look for.
	 */
	function __construct($className) {
		$this->className = $className;
	}

	/**
	 * @inheritdoc
	 *
	 * @return array
	 */
	function check() {
		if(class_exists($this->className)) return array(EnvironmentCheck::OK, 'Class ' . $this->className.' exists');
		else return array(EnvironmentCheck::ERROR, 'Class ' . $this->className.' doesn\'t exist');
	}
}