Measuring conducted emission is the simplest and most affordable method of getting some indication of whether a design can meet EMI/EMC requirements. A Line Impedance Stabilization Network (LISN) like the one presented in this video is an indispensable part of this.

In cooperation with Würth Elektronik, Elektor has developed a 5 µH, 50 Ω dual DC LISN that supports voltages up to 60 V and currents up to 10 A. The Dual DC LISN comes as a kit of parts. This video shows one way of assembling it.
 

Resources

What to do with a LISN is described in the articles listed below: