public void TestUniqueCharacterAtTheEnd()
        {
            string input = "aaababc";
            FindFirstUniqueCharacterInString c = new FindFirstUniqueCharacterInString();
            var output = c.GetFirstUniqueCharacterInString(input);

            Assert.AreEqual('c', output);
        }
        public void TestOneCharacterArray()
        {
            string input = "a";
            FindFirstUniqueCharacterInString c = new FindFirstUniqueCharacterInString();
            var output = c.GetFirstUniqueCharacterInString(input);

            Assert.AreEqual('a', output);
        }