public void testShift()
 {
     StringTheory theory = new StringTheory("mares");
     Assert.True(theory.Shift() == 'm', "shift failed (m)");
     Assert.True(theory.Shift() == 'a', "shift failed (a)");
     Assert.True(theory.Shift() == 'r', "shift failed (r)");
     Assert.True(theory.Shift() == 'e', "shift failed (e)");
     Assert.True(theory.Shift() == 's', "shift failed (s)");
 }