An exam for politicians?

You have to pass a test to sell securities, to be an appraiser, to sell real estate, to get a teaching degree, to be a doctor, a lawyer, a contractor, electrician or plumber. Why don't politicians have to pass a test that would evaluate their knowledge of economics, world politics, governmental processes and the constitution? Popularity has little to do with the qualification to govern. Before entering any race for congress or senate their should be an exam that must be past in order start a campaign. It would save millions if not billions of dollars spent on ridiculous hearings where congress asks the same stupid questions over and over again. This week's hearing could have been done by just having a video of Paulson and Bernake giving the same answers over and over again while all of congress had to sit there, watch and take notes. When voter turnout has dropped to 50% at times or below it is clear that main street America has lost faith in our elected officials maybe a test would help improve the quality of our public servants.