public void PersonFullName_FullNameReverse_Returns_Correct_String()
        {
            // Arrange
            string firstName = "John";
            string lastName  = "Doe";

            // Act
            var personFullName = new PersonFullName(firstName, lastName);

            // Assert
            Assert.Equal("Doe, John", personFullName.FullNameReverse);
        }
        public void PersonFullName_Given_Valid_Names_Is_Valid()
        {
            // Arrange
            string firstName = "John";
            string lastName  = "Doe";

            // Act
            var personFullName = new PersonFullName(firstName, lastName);

            // Assert
            Assert.Equal(personFullName.First, firstName);
            Assert.Equal(personFullName.Last, lastName);
        }