public void FindByDate_GivenItemsExist_ShouldReturnMatchingItems() { //Given var tournamentRepository = Substitute.For <ITournamentRepository>(); var tournamentService = new TournamentService(tournamentRepository); var tournaments = new List <Tournament>() { new Tournament(1, "Tournament 1", DateTime.Parse("2018/10/18"), "Location 1"), new Tournament(2, "Tournament 2", DateTime.Parse("2019/12/25"), "Location 2"), new Tournament(3, "Tournament 3", DateTime.Parse("2016/01/01"), "Location 3") }; tournamentRepository.FindByDate(Arg.Any <DateTime>()).Returns(tournaments); //When var results = tournamentService.FindByDate(DateTime.Parse("2018/10/18")); //Then results.Should().BeEquivalentTo(tournaments); }