public void TestTwoMatchingCharacters()
{
List <string> inputs = new List <string> {
"xyxy", "aabcdefgaa"
};
Santa santa = new Santa();
foreach (string input in inputs)
{
Assert.AreEqual(true, santa.MatchTwoLetters(input), input);
}
Assert.AreNotEqual(true, santa.MatchTwoLetters("aaa"), "aaa");
}