public void CanChangeEMailToNull()
    {
      // Arrange
      User u = new User("Bent", null, "*****@*****.**", UserNameValidator, null);

      // Act
      u.ChangeEMail(null);

      // Assert
      Assert.IsNull(u.EMail);
    }
    public void CanChangeEMail()
    {
      // Arrange
      User u = new User("Bent", null, null, UserNameValidator, EmptyPasswordPolicy);

      // Act
      u.ChangeEMail("*****@*****.**");

      // Assert
      Assert.AreEqual("*****@*****.**", u.EMail);
    }