Coding Kata of After Work Hacking: URL Splitting, http://sites.google.com/site/tddproblems/all-problems-1/URL-splitting

Implementation (still has code duplication in extraction methods)

<?php
class Url {

	public $protocol = "";
	public $domain = "";
	public $path = "";

	public function __construct($url_string){
		$this->protocol = $this->_extractProtocol($url_string);	
		$this->domain = $this->_extractDomain($url_string);
		$this->path = $this->_extractPath($url_string);
	}

	private function _extractProtocol($url_string) {
		preg_match("~^(\w*)://.*~", $url_string, $matches);
		$protocol = '';
		if(isset($matches[1])) {
			$protocol = $matches[1];
		}
		return $protocol;
	}

	private function _extractDomain($url_string){
		preg_match("~^(\w*://)?([^:/]+)~", $url_string, $matches);
		
		$domain = $matches[2];
		return $domain;
	}
	
	private function _extractPath($url_string) {
		preg_match("~^(\w*://)?([^/]+)[/]?(.*)~", $url_string, $matches);
		$path = $matches[3];
		return $path;	
	}
}

Tests

<?php

include "SplitUrl.php";

class UrlSplittingTest extends PHPUnit_Framework_TestCase {
	public function testUrlWithNoProtocol() {
		$url = "www.noprotocol.com";
		$expected = "";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->protocol);
	}

	public function testGetProtocolFromUrlWithProtocol(){
		$url = "http://google.de";
		$expected = "http";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->protocol);
	}

	public function testGetProtocolFromUrlWithoutProtocolAndWithPort() {
		$url = "google.de:8080";
		$expected = "";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->protocol);
	}

	public function testGetDomainNameFromUrlWithoutProtocolAndWithoutPath() {
		$url = "www.google.de";
		$expected = "www.google.de";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->domain);
	}
	public function testDomainNameFromUrlWithProtocolAndWithoutPath() {
		$url = "http://www.google.de";
		$expected = "www.google.de";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->domain);

	}

	public function testDomainNameFromUrlWithProtocolAndWithPath() {
		$url = "http://www.google.de/test";
		$expected = "www.google.de";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->domain);
	}

	public function testDomainNameFromUrlWithProtocolAndWithPathAndWithPort() {
		$url = "http://www.google.de:80/test";
		$expected = "www.google.de";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->domain);
	}

	public function testPathFromUrlWithoutPath() {
		$url = "http://www.google.de";
		$expected = "";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->path);
	}

	public function testPathFromUrlWithPath() {
		$url = "http://www.google.de/test";
		$expected = "test";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->path);
	}

	public function testPathFromUrlWithMultiLevelPath() {
		$url = "http://www.google.de/test/test2";
		$expected = "test/test2";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->path);
	}

	public function testPathFromUrlWithMultiLevelPathAndPort() {
		$url = "http://www.google.de:80/test/test2";
		$expected = "test/test2";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->path);
	}

	public function testPathFromUrlWithoutProtocol() {
		$url = "www.google.de/test/test2";
		$expected = "test/test2";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->path);
	}

	public function testProtocolWhenFTP() {
		$url = "ftp://www.google.de/test/test2";
		$expected = "ftp";
		$url_object = new Url($url);

		$this->assertEquals($expected, $url_object->protocol);
	}
}