Render guid with isPermaLink=false

Swaps behaviour to match the specs at http://cyber.law.harvard.edu/rss/rss.html#ltguidgtSubelementOfLtitemgt
"isPermaLink is optional, its default value is true".  Fix existing unittest to look for no "isPermalink" attribute
when the value is true, add a new test to look for it when it's false.

Author: barryp

src/Suin/RSSWriter/Item.php

@@ -108,8 +108,8 @@ public function asXML()
         if ($this->guid) {
             $guid = $xml->addChild('guid', $this->guid);
 
-            if ($this->isPermalink) {
-                $guid->addAttribute('isPermaLink', 'true');
+            if ($this->isPermalink === false) {
+                $guid->addAttribute('isPermaLink', 'false');
             }
         }
 

tests/Suin/RSSWriter/ItemTest.php

@@ -143,7 +143,52 @@ public function testAsXML()
 			<description>{$data['description']}</description>
 			<category>{$data['categories'][0][0]}</category>
 			<category domain=\"{$data['categories'][1][1]}\">{$data['categories'][1][0]}</category>
-			<guid isPermaLink=\"true\">{$data['guid']}</guid>
+			<guid>{$data['guid']}</guid>
+			<pubDate>{$nowString}</pubDate>
+			<enclosure url=\"{$data['enclosure']['url']}\" type=\"{$data['enclosure']['type']}\" length=\"{$data['enclosure']['length']}\"/>
+			<author>{$data['author']}</author>
+		</item>
+		";
+        $this->assertXmlStringEqualsXmlString($expect, $item->asXML()->asXML());
+    }
+
+    public function testAsXML_false_permalink()
+    {
+        $now = time();
+        $nowString = date(DATE_RSS, $now);
+
+        $data = array(
+            'title' => "Venice Film Festival Tries to Quit Sinking",
+            'url' => 'http://nytimes.com/2004/12/07FEST.html',
+            'description' => "Some of the most heated chatter at the Venice Film Festival this week was about the way that the arrival of the stars at the Palazzo del Cinema was being staged.",
+            'categories' => array(
+                array("Grateful Dead", null),
+                array("MSFT", 'http://www.fool.com/cusips'),
+            ),
+            'guid' => "http://inessential.com/2002/09/01.php#a2",
+            'isPermalink' => false,
+            'pubDate' => $now,
+            'enclosure' => array(
+                'url' => 'http://link-to-audio-file.com/test.mp3',
+                'length' => 4992,
+                'type' => 'audio/mpeg'),
+            'author' => 'Hidehito Nozawa aka Suin'
+        );
+
+        $item = new Item();
+
+        foreach ($data as $key => $value) {
+            $this->reveal($item)->attr($key, $value);
+        }
+
+        $expect = "
+		<item>
+			<title>{$data['title']}</title>
+			<link>{$data['url']}</link>
+			<description>{$data['description']}</description>
+			<category>{$data['categories'][0][0]}</category>
+			<category domain=\"{$data['categories'][1][1]}\">{$data['categories'][1][0]}</category>
+			<guid isPermaLink=\"false\">{$data['guid']}</guid>
 			<pubDate>{$nowString}</pubDate>
 			<enclosure url=\"{$data['enclosure']['url']}\" type=\"{$data['enclosure']['type']}\" length=\"{$data['enclosure']['length']}\"/>
 			<author>{$data['author']}</author>