You cannot test for repeaters

What I expected to happen was to have the testforblock command "/testforblock ~ ~ ~ minecraft:repeater" to work but there is no name for repeater in the command(meaning if you press tab it will not show up. ...:
Describe what you thought should happen here

What actually happened was nothing...:
Describe what happened here

Steps to Reproduce:
1. place a repeater down on any block
2. type the command "/testforblock [x,y,x] minecraft:" and try to find repeater, it is not there
3.