Fixing tie breaker bug

The tie breaker value was being used even in cases where the tie breaker
did not appear in the list of best match ties. This commit fixes this,
so that the tie breaker is used only if it appears within the list of
tied best matches.

src/Bitworking/Mimeparse.php

@@ -243,7 +243,7 @@ public static function bestMatch($supported, $header, $tieBreaker = null)
             $ties = array_filter($weightedMatches, function ($val) use ($a) {
                 return ($val[0] == $a[0]);
             });
-            if (count($ties) > 1) {
+            if (count($ties) > 1 && in_array(array($a[0], $tieBreaker), $ties)) {
                 return $tieBreaker;
             }
         }

tests/Bitworking/MimeparseTest.php

@@ -214,4 +214,15 @@ public function testBestMatchWithTieBreakerAndNoTies()
 
         $this->assertEquals('application/hal+json', Mimeparse::bestMatch($supportedMimeTypes, $httpAcceptHeader, 'application/hal+json'));
     }
+
+    /**
+     * @covers Bitworking\Mimeparse::bestMatch
+     */
+    public function testBestMatchWithTieBreakerNotMatchingTies()
+    {
+        $supportedMimeTypes = array('text/html', 'application/hal+xml', 'application/hal+json');
+        $httpAcceptHeader = 'application/*';
+
+        $this->assertEquals('application/hal+xml', Mimeparse::bestMatch($supportedMimeTypes, $httpAcceptHeader, 'text/html'));
+    }
 }