public void MorseCode()
        {
            MorseCode cipher = new MorseCode();

            const string plaintext  = "MORSE CODE";
            const string ciphertext = "-- --- .-. ... .   -.-. --- -.. .";

            Assert.AreEqual(ciphertext, cipher.Encrypt(plaintext));
            Assert.AreEqual(plaintext, cipher.Decrypt(ciphertext), true);
        }