public void What_is_previous_value_of_A()
{
ILearning a = new Alphabet('A');
string expected = "Z";
string actual = a.Previous();
Assert.AreEqual(expected, actual);
}
public void What_is_NextLetter_after_Z()
{
ILearning a = new Alphabet('Z');
string expected = "A";
string actual = a.Next();
Assert.AreEqual(expected, actual);
}
