Test and fix for duplicate URLs in the rels object

Author: Zegnat

Mf2/Parser.php

@@ -1295,7 +1295,11 @@ public function parseRelsAndAlternates() {
 			}
 
 			foreach ($linkRels as $rel) {
-				$rels[$rel][] = $href;
+				if (!array_key_exists($rel, $rels)) {
+					$rels[$rel] = array($href);
+				} elseif (!in_array($href, $rels[$rel])) {
+					$rels[$rel][] = $href;
+				}
 			}
 
 			if (!array_key_exists($href, $rel_urls)) {

tests/Mf2/RelTest.php

@@ -200,4 +200,13 @@ public function testRelURLsInfoMergesCorrectly() {
     $this->assertEquals($output['rel-urls']['#']['text'], 'This nodeValue');
   }
 
+  public function testRelURLsNoDuplicates() {
+    $input = '<a href="#a" rel="a"></a>
+<a href="#b" rel="a"></a>
+<a href="#a" rel="a"></a>';
+    $parser = new Parser($input);
+    $output = $parser->parse();
+    $this->assertEquals($output['rels']['a'], ['#a', '#b']);
+  }
+
 }