example.php

<?php
require("phpmock.php");
class foo extends PHPUnit_PHPMock {
   function testbar() {
	  $php = self::getMock('php', array('time'));
	  $php->expects(self::once())->method('time')->will(self::returnValue(32));
	  echo time();
   }
}

phpmock.php

<?php
/**
 * Enables mocking of functions (internal & user)
 * 
 * $oPHP = self::getMock('php, array('file_put_contents'));
 * $oPHP->expects(self::once())
 * 	->method('file_put_contents')
 * 	->with('foo', 'bar')
 * 	->will(self::returnValue(true));
 *
 * 	file_put_contents('foo', 'bar');
 */

class php {
	static protected $aOverloaded = array();
	static protected $oInstance = null;
	
	static public function getInstance() {
		if (self::$oInstance == null) {
			self::$oInstance = new self;
		}
		return self::$oInstance;
	}
	
	static public function setInstance($oInstance) {
		self::$oInstance = $oInstance;
	}
	
	static public function _override($sMethod) {
		$sOverload = <<<CODE
		function $sMethod () {
		\$aArgs = func_get_args();
		\$aMethod = array(php::getInstance(), '$sMethod');
		\$mReturn = call_user_func_array(\$aMethod, \$aArgs);
		return \$mReturn;
		}
CODE;
		$sNew = "__php_$sMethod";
		
		if (!function_exists($sNew)) {
			rename_function($sMethod, $sNew);
			eval ($sOverload);
			self::$aOverloaded[] = $sMethod;
		}
	}
	
	/**
	 * Restores all functions to original. Segfault on process end without this?
	 */
	function _restore() {
		foreach(self::$aOverloaded as $sKey => $sFunction) {
			rename_function($sFunction, uniqid($sFunction));
			rename_function('__php_'.$sFunction, $sFunction);
		}
		self::$aOverloaded = array();
	}
	function __call($sMethod, $aArgs) {
		return call_user_func_array('__php_' . $sMethod, $aArgs);
	}
}
register_shutdown_function(function() {
	php::_restore();
});

class PHPUnit_PHPMock extends PHPUnit_Framework_TestCase {
	public function getMock($sClass, $aMethods) {
		if ($sClass == 'php') {
			php::_restore();
			foreach($aMethods as $sMethod) {
				php::_override($sMethod);
			}
		}
		$oInstance = call_user_func_array(array('parent', 'getMock'), func_get_args());
		if ($sClass == 'php') {
			php::setInstance($oInstance);
		}
		return $oInstance;
	}
}