gistfile1.php

<?php
// given a class that looks like this:
class User {
	public function __construct($id=false) {
		if ($id > 0) {
			$userRow = db::getRow('SELECT * FROM users WHERE id = '.$id);
			if (!$userRow)
				return false;
			foreach ($userRow as $k=>$v){
				if (property_exists($this, $k)){
						$this->$k = $v;
				}
			}
		}
	}
}



// mock the DB static
class db {
	static public $fail = false;
	static private $testValues = array(
		'user'=>array('first_name'=>'Bob', 'last_name'=>'Franklin'),
		'otherThing'=>array('valid'=>'values')
	);
	static public $testWhat = 'user';
	static function getRow($sql){
		if (self::$fail === false)
			return self::$testValues[self::$testWhat];
		return array();
	}
}


// in tests:

// works
db::$testWhat = 'user';
$SUT = new User(10); 
//... test continues


// failing test
db::$fail = true;
db::$testWhat = 'user';
$SUT = new User(10);