Add test case for empty string

Author: youkidearitai

ext/mbstring/tests/mb_trim.phpt

@@ -53,6 +53,11 @@ var_dump(mb_ltrim("\u{FFFE}漢字", "\u{FFFE}\u{FEFF}"));
 var_dump(bin2hex(mb_ltrim(mb_convert_encoding("\u{FFFE}漢字", "UTF-16LE", "UTF-8"), mb_convert_encoding("\u{FFFE}\u{FEFF}", "UTF-16LE", "UTF-8"), "UTF-16LE")));
 var_dump(bin2hex(mb_ltrim(mb_convert_encoding("\u{FEFF}漢字", "UTF-16BE", "UTF-8"), mb_convert_encoding("\u{FFFE}\u{FEFF}", "UTF-16BE", "UTF-8"), "UTF-16BE")));
 
+echo "== Empty string ==\n";
+var_dump(mb_trim(" abcd ", ""));
+var_dump(mb_ltrim(" abcd ", ""));
+var_dump(mb_rtrim(" abcd ", ""));
+
 echo "== SJIS ==\n";
 var_dump(mb_convert_encoding(mb_trim("\x81\x40\x82\xa0\x81\x40", "\x81\x40", "SJIS"), "UTF-8", "SJIS"));
 
@@ -108,6 +113,10 @@ string(0) ""
 string(6) "漢字"
 string(8) "226f575b"
 string(8) "6f225b57"
+== Empty string ==
+string(6) " abcd "
+string(6) " abcd "
+string(6) " abcd "
 == SJIS ==
 string(3) "あ"
 == Same strings ==