Compare upper and lower case letters with the Turkish culture.

LocalizationTests.cs

[TestMethod]
public void TestTurkishStringCompare()
{
    const string lowerCharacters = "abcdefghijklmnopqrstuvwxyz";
    const string upperCharacters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    var turkishCulture = CultureInfo.GetCultureInfo("tr-TR");

    var upper = lowerCharacters.ToUpper(turkishCulture);
    var lower = upperCharacters.ToLower(turkishCulture);

    Assert.AreNotEqual(upper, lower);
}