If someone gave you a set of unassembled Ikea stuff and you didn't know if you could use it until you assembled it. Who should pay for the assembly of the stuf

If someone gave you a set of unassembled Ikea stuff and you didn't know if you could use it until you assembled it. Who should pay for the assembly of the stuff ? Would you put it together for free just to decide ? Who pays for the used resources ?