Added tests for audio concatenation

tests/Functional/AudioConcatenationTest.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace Tests\FFMpeg\Functional;
+
+use FFMpeg\Format\Audio\Mp3;
+use FFMpeg\Media\Audio;
+
+class AudioConcatenationTest extends FunctionalTestCase
+{
+    public function testSimpleAudioFileConcatTest()
+    {
+        $ffmpeg = $this->getFFMpeg();
+        
+        $files = [
+            __DIR__ . '/../files/Jahzzar_-_05_-_Siesta.mp3',
+            __DIR__ . '/../files/02_-_Favorite_Secrets.mp3',
+        ];
+
+        $audio = $ffmpeg->open(current($files));
+
+        $this->assertInstanceOf('FFMpeg\Media\Audio', $audio);
+        
+        $filename = __DIR__ . '/output/concat-output.mp3';
+
+        if (is_file($filename)) {
+            unlink($filename);
+        }
+
+        $audio->concat($files)->saveFromSameCodecs($filename, TRUE);
+        
+        $this->assertFileExists($filename);
+        unlink($filename);
+    }
+}