Improve unit test

Author: Manunchik

tests/PhpWord/MediaTest.php

@@ -34,6 +34,22 @@ public function testGetSectionMediaElementsWithNull()
         $this->assertEquals(array(), Media::getElements('section'));
     }
 
+    /**
+     * Get header media elements
+     */
+    public function testGetHeaderMediaElementsWithNull()
+    {
+        $this->assertEquals(array(), Media::getElements('header'));
+    }
+
+    /**
+     * Get footer media elements
+     */
+    public function testGetFooterMediaElementsWithNull()
+    {
+        $this->assertEquals(array(), Media::getElements('footer'));
+    }
+
     /**
      * Count section media elements
      */