public void Rotate13FxTest4()
 {
     Assert.AreEqual("P# vf pbby!", Rotate13.Rotate13Fx("C# is cool!"));
 }
 public void Rotate13FxTest2()
 {
     Assert.AreEqual("10 + 2 vf gjryir.", Rotate13.Rotate13Fx("10 + 2 is twelve."));
 }
 public void Rotate13FxTest3()
 {
     Assert.AreEqual("Pbqrjnef", Rotate13.Rotate13Fx("Codewars"));
 }
 public void Rotate13FxTest1()
 {
     Assert.AreEqual("grfg", Rotate13.Rotate13Fx("test"));
     Assert.AreEqual("Grfg", Rotate13.Rotate13Fx("Test"));
 }