static void AssertContains(string a, string b, bool caseSensitiveEquals, bool caseInsenstaiveEquals)
{
var asciiA = new AsciiString(a);
var asciiB = new AsciiString(b);
Assert.Equal(caseSensitiveEquals, AsciiString.Contains(asciiA, asciiB));
Assert.Equal(caseInsenstaiveEquals, AsciiString.ContainsIgnoreCase(asciiA, asciiB));
}