Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
Q&A for work
Connect and share knowledge within a single location that is structured and easy to search.
Is there some test/tests that I can easily use to gauge my level of "proficiency"?
Without going to some costly test.
Use the language for whatever purpose you intend to and see how well it goes. This should give you a pretty good idea of your abilities.