An efficient way of testing your knowledge is to try and explain the subject in simple words. If you're unable to do that you haven't understood the subject well enough. Identify where your knowledge is lacking and study those areas more until you can explain them in simple words.
You should be able to get your point across in as few words as possible, but don't overthink your first draft. Publish it then go over it again and make changes.
This is the basis of [[Richard Feynman]]'s learning technique