Add validation of Return/Cancel URL's (with test cases)

tests/PayPal/Test/Api/RedirectUrlsTest.php

@@ -0,0 +1,42 @@
+<?php
+namespace PayPal\Test\Api;
+
+use PayPal\Api\RedirectUrls;
+
+class RedirectUrlsTest extends \PHPUnit_Framework_TestCase {
+
+	public function validRedirectUrlsProvider() {
+		return array(
+			array('https://devtools-paypal.com/guide/pay_paypal/php?success=true', 'https://devtools-paypal.com/guide/pay_paypal/php?cancel=true')
+		);
+	}
+
+	public function invalidRedirectUrlsProvider() {
+		return array(
+			array('devtools-paypal.com/guide/pay_paypal/php?success=true', 'devtools-paypal.com/guide/pay_paypal/php?cancel=true')
+		);
+	}
+
+	/**
+	 * @dataProvider validRedirectUrlsProvider
+	 */
+	public function testValidRedirectUrls($return_url, $cancel_url) {
+		$redirectUrls = new RedirectUrls();
+		$redirectUrls->setReturn_url($return_url);
+		$redirectUrls->setCancel_url($cancel_url);
+
+		$this->assertEquals($return_url, $redirectUrls->getReturnUrl());
+		$this->assertEquals($cancel_url, $redirectUrls->getCancelUrl());
+	}
+
+	/**
+	 * @dataProvider invalidRedirectUrlsProvider
+	 */
+	public function testInvalidRedirectUrls($return_url, $cancel_url) {
+		$redirectUrls = new RedirectUrls();
+		$this->setExpectedException('\InvalidArgumentException');
+		$redirectUrls->setReturnUrl($return_url);
+		$redirectUrls->setCancelUrl($cancel_url);
+	}
+
+}