public void ATMController_EventFired_AirspaceFilterCalled() { // Arrange _uut.airspaceFilter_ = _fakeFilter; _fakeFilter.CheckAirspace(Arg.Any <List <Track> >()).Returns(new List <Track>()); _rawList.Add("ATR423;39045;12932;14000;20151006213456789;false;North;0"); // Act _fakeTransponderReceiver.TransponderDataReady += Raise.EventWith(new RawTransponderDataEventArgs(_rawList)); // Assert _fakeFilter.Received(1).CheckAirspace(Arg.Is <List <Track> >(l => l.Count == 1)); }