public void TrimEndTest(string s)
{
Utf8String u8s = new Utf8String(s);
string expected = s.TrimEnd();
Utf8String u8expected = new Utf8String(expected);
Utf8String u8trimmed = u8s.TrimEnd();
Assert.Equal(u8expected, u8trimmed);
string trimmed = u8trimmed.ToString();
Assert.Equal(expected, trimmed);
}