public void ReplaceSegment_04() { // arrange: ILeg leg = MockRepository.GenerateStrictMock <ILeg>(); Itinerary empty = new Itinerary(); IItinerary tested = empty.Append(leg); // act: Assert.Throws <ArgumentNullException>(delegate { tested.ReplaceSegment(null); }); // assert: leg.VerifyAllExpectations(); }