Clean up output dir before running new tests.

tests/_bootstrap.php

@@ -13,3 +13,22 @@ if (!function_exists('__')) {
     $translator = new \Gettext\Translator();
     $translator->register();
 }
+
+// Clear output directory
+function rrmdir($dir)
+{
+    if (is_dir($dir)) {
+        $objects = array_diff(scandir($dir, SCANDIR_SORT_NONE) ?: [], ['.', '..', '.gitignore']);
+        foreach ($objects as $object) {
+            if (is_dir($dir . '/' . $object)) {
+                rrmdir($dir . '/' . $object);
+            } else {
+                unlink($dir . '/' . $object);
+            }
+        }
+        reset($objects);
+        @rmdir($dir);
+    }
+}
+
+rrmdir(__DIR__ . '/_output');