public void Test()
{
var order = new Mock <IOrder>();
order.Setup(n => n.AttachAsModifiedToOrders(It.IsAny <IOrder>()));
var manipulator = new Manipulator(order.Object);
manipulator.DoStuff();
order.Verify(x => x.AttachAsModifiedToOrders(It.IsAny <IOrder>(), It.IsAny <Expression <Func <IOrder, object[]> > >()), Times.Once());
}