adding test

Author: devnexen

ext/gettext/tests/gh17400.phpt

@@ -0,0 +1,19 @@
+--TEST--
+Bug #53251 (bindtextdomain with null dir doesn't return old value)
+--EXTENSIONS--
+gettext
+--CREDITS--
+YuanchengJiang
+--FILE--
+<?php
+$utf16_first_le = pack("H*", "00d800dc");
+$utf16le_char_bad = pack("H*", "00dc00dc");
+
+try {
+	bindtextdomain($utf16le_char_bad,$utf16_first_le);
+} catch (\ValueError $e) {
+	echo $e->getMessage();
+}
+?>
+--EXPECT--
+bindtextdomain(): Argument #1 ($domain) cannot be empty