is($html, $exp, 'only obfuscated relevant addresses');
-is('foo-bar', PublicInbox::Hval::to_filename('foo bar '),
+is(PublicInbox::Hval::to_filename('foo bar '), 'foo-bar',
'to_filename has no trailing -');
-is('foo-bar', PublicInbox::Hval::to_filename("foo bar\nanother line\n"),
+is(PublicInbox::Hval::to_filename("foo bar\nanother line\n"), 'foo-bar',
'to_filename has no repeated -, and nothing past LF');
-is('foo.bar', PublicInbox::Hval::to_filename("foo....bar"),
+is(PublicInbox::Hval::to_filename("foo....bar"), 'foo.bar',
'to_filename squeezes -');
+is(PublicInbox::Hval::to_filename(''), undef, 'empty string returns undef');
+
my $s = "\0\x07\n";
PublicInbox::Hval::src_escape($s);
is($s, "\\0\\a\n", 'src_escape works as intended');