public void RegisterAsSold_AddsSellDateToBallot()
{
// Arrange
var expectedDateTime = new DateTime(2018, 01, 01);
SystemTime.SetDateTime(expectedDateTime);
var ballot = new Ballot
{
Id = 1,
Number = 1234,
};
// Act
ballot.RegisterAsSold();
// Assert
ballot.Id.Should().Be(ballot.Id);
ballot.Number.Should().Be(ballot.Number);
ballot.SellDate.Should().Be(expectedDateTime);
}