What if it is a test about knowledge ? Economists, politicians, even physicist don't agree with each others, but they are knowledgeable about their fields. They know what are the existing theories, and they know what can be considered a fact.
The problem with this is it create an oligarchy (which may not be a bad thing), and it place the power of deciding who acceed to the oligarchy to its members.
It can be good. The actual best system of government (IMO) is a tyrany/oligarchy where people in power work for the greater good, but it is difficult to achieve and unstable (what if the successor don't have great intention ?)
The other way is to have a direct democracy, but many people in the population don't have time to think about new laws, and to gain knowledge on specifics subjects, so they delegate to representatives.
If the check and balances work in this new indirect democratic system, and the majority of people are educated enough to choose their representative wisely, we have a working system.
We shouldn't put tests to access to voting, we should make sure most voters would be able to pass them, by having a good educating system.