When leaders ignore history, society will repeat the sins of its past. It is a simple concept that isn't hard to grasp considering how it is a natural process. If a child burns their hand they learn not to touch the fire, if a leader falls for a specific leader, his successors should learn from his errors.
We are losing faith in our Congressmen and Representatives because it is clear that they are not doing what they say they are and working in our best interests. Sometimes it's because these people that we have elected to office are better actors and businessmen than actual government leaders, and there should be a standard they need to be set to.
I do not agree with this proposal. How that test is administered and what subjects it covers would be something determined by people with a vested interest in maintaining the political status quo. We would quickly get unfair tests that favor one party over another, or one party's view of history.
It would be a burdensome rule for Congressional candidates to have to pass an American History test. I can't see this ever being required or who would even take the initiative to pass this type of law. That being said, I think they all should be knowledgeable about the country's history and current law, and that they can be "tested" in a way, such as during debates and interviews.
Although it is useful for a politician to be knowledgeable about their history, it does not make or break their ability to serve their people. They should be in the capital working for their citizens and pressing the issues that need to be tackled, and it seems silly to think that a history lesson is needed to accomplish that.