public function testStringExtraction() {
		$result = String::extract('/string/', 'whole string');
		$this->assertEqual('string', $result);

		$this->assertFalse(String::extract('/not/', 'whole string'));
		$this->assertEqual('part', String::extract('/\w+\s*(\w+)/', 'second part', 1));
		$this->assertNull(String::extract('/\w+\s*(\w+)/', 'second part', 2));
	}