public void Get_InCorrectInputDiseaseId_ReturnNull() { // Arrange TestData testData = new TestData(); var mockDataProvider = new Mock <IDataAccessManager>(); mockDataProvider.Setup(mock => mock.GetDisease(testData.disease.DiseaseId)).Returns(testData.disease); var service = new DiseaseManager(mockDataProvider.Object); // Act Disease disease = service.Get(testData.disease.DiseaseId + 1); // Assert Assert.IsNull(disease); }