AFCIs are devices that purport to detect arcs and shut down the circuit. They often get compared to GFCIs (RCD for you folks) when people resist the change. The major difference is that ground fault devices are designed to a definite standard. A certain leakage will trip them. On the other hand AFCIs do not have any standard for what an arc really is and use proprietary methodologies to identify arcs. Something that will trip one brand may not be detected by another brand and there is no universal testing method. Even if the manufacturer was selling a tester for their device, it would really just be testing their method of detecting arcs, not whether another arcing situation would be detected.
