Congrats! I've always thought it was a little silly to make them take a test that many citizens couldn't pass anyway. I believe that the desire to be a citizen should be enough.
Congrats to your dad. I think it is wonderful that he cared enough to study and learn about the country that he chose to call home. The desire to be a citizen is not enough, you have to value the country you want to become a citizen of enough to learn about that country so that you can assimilate into it and make yourself a future. I'm very proud of those who care enough to do it!