public void GetUnitById_ShouldReturn_NotNull() { // Arrange fakeUnitsRepository.Setup(a => a.GetById(1)).Returns(new UnitsModel()); unitsService = new UnitsService(fakeUnitsRepository.Object); UnitsDtoModel unitDto = null; try { // Act unitDto = unitsService.GetUnitById(1); } catch (Exception ex) { errorMessage = ex.Message + " | " + ex.StackTrace; } // Assert Assert.IsNotNull(unitDto, errorMessage); }