public void OnlyIncludeElementsOfTheSpecifiedTypeAndDerivedTypes()
{
var trucks = new[] { new Truck(), new Truck(), new HeavyDutyTruck() };
var autos = new Automobile[] { trucks[0], trucks[1], trucks[2], new Car(), new Car(), new SportUtilityVehicle() };
var filteredTrucks = autos.OfType <Truck>();
Assert.Equal(3, filteredTrucks.Count());
Assert.Contains(filteredTrucks, t => object.ReferenceEquals(t, trucks[0]));
Assert.Contains(filteredTrucks, t => object.ReferenceEquals(t, trucks[1]));
Assert.Contains(filteredTrucks, t => object.ReferenceEquals(t, trucks[2]));
}
