Allow optional directories

run-tests.php

@@ -313,7 +313,13 @@ $exts_tested = count($exts_to_test);
 $exts_skipped = 0;
 $ignored_by_ext = 0;
 sort($exts_to_test);
-$test_dirs = array('tests', 'pear', 'ext');
+$test_dirs = array('tests', 'ext');
+$optionals = array('pear', 'Zend', 'ZendEngine2');
+foreach($optionals as $dir) {
+	if (@filetype($dir) == 'dir') {
+		$test_dirs[] = $dir;
+	}
+}
 
 foreach ($test_dirs as $dir) {
 	find_files("{$cwd}/{$dir}", ($dir == 'ext'));