public void ShouldntFindASummaryAndShouldReturnAnErrorCode() { // Arrange var mockVacancySummaryService = new Mock <IVacancySummaryService>(); mockVacancySummaryService.Setup(x => x.GetById(It.IsAny <int>())).Returns(null as VacancySummary); var sut = new VacancyManagementService(null, null, mockVacancySummaryService.Object); // Act var result = sut.FindSummary(1); // Assert Assert.AreEqual(VacancyManagementServiceCodes.FindSummary.NotFound, result.Code); mockVacancySummaryService.VerifyAll(); }