The ultimate fluency test
Visiting or (or even moving) to the country native to the language you've just learned is the best way to go full immersion and put your skills to the test, so...
What are your experiences using the language(s) you have learned in the countries where that language is spoken... i.e. speaking with natives? Did you get along well, or did you use a lingua franca (most likely English) most of the time? Or was Google Translate (or any other similar service) still your best help?
If you haven't yet, do you have any plans of doing so in the next couple of years?
Yes, visiting the country where your target language is spoken is a good test, but you have to maintain your private study and keep exposing yourself to new material. You may think that happens automatically when being surrounded by native speakers, but the sad fact is that many people will know English well enough (in Europe at least). And even if they don't: mastering a language goes further than ordering food or asking the way, so you have to find ways to push yourself further.
Having that said, I think it's fair also to name some advantages of being abroad. Bookstores, for example, are a treasure mine of material you wouldn't find in your bookstores at home; even though it has become easier to order foreign books online, it's still amazing to wander about in a bookstore and touch and look at the printed editions themselves. Doing groceries and preparing food are other ways of exposure you wouldn't get at home, especially when using recipes in the language you're learning.
I've been in Italy for the past few months, and I find that I am at comfort the most when talking to my housemates, the non-Italian ones, who also still struggle with expressing themselves in Italian, but are eager to learn like me. I don't feel as self-conscious around them compared to Italians themselves; when they switch to English, I feel stupid for not understanding them - and to be honest, just talking slower is often enough - but when the non-Italians switch to English, I simply regard it as a sign that we're talking about more complex matter for which we both feel our basic conversation skills in Italian don't suffice anymore at that moment.
I've been to UK once, and my English worked well enough that time. But I had spent ages learning it by then...
Hopefully, in the next couple of years I'll be ready to give my German a careful try. Right now I'm only 6 weeks in it and it's understandably not working yet.
Btw, it's my favorite game when abroad to make people who don't know where I am from try and guess that. So far no one has got it right in the standard three tries I give them, not even close, haha! :D
Russland ist ein großes Land.
Straight from the exercise I just did.
(I read your answer above, but can't reply there)
With my own semester of college Portuguese and Spanish competence I found myself... essentially completely stymied in Portugal (of course, I could read things) until I encountered a Brazilian guy standing outside a bus station. With him I could converse with ease. Accents: they matter :) (I'd studied Brazilian Portuguese.)
I went to Georgia and Armenia with a certain amount of Russian, but nowhere near fluency. The situation in Georgia is unique because many people speak Russian (and at least some tiny sliver of the populace only speaks Russian) and few speak English; however, it felt weird in a way trying to use a language I was far from fluent in, and then there's the politics, as this wasn't so long after the mini-war. So sometimes it wasn't too clear which language I should try using. Normally I could say what I needed to say in Russian and understand the reply, at least the second time. But I didn't manage to get past the awkwardness, and it didn't seem like most people particularly felt like speaking Russian even if it was the only chance we had to communicate. Of course, how much Russian they actually knew is an unknowable.
Things were more straightforward language-wise in Armenia. Many, many things are written in Russian instead of Armenian (maybe even 3/4 of all the signs were in Russian), so it felt much more normal just walking up to people and speaking Russian. Russian, unsurprisingly, was the lingua franca for the mini-bus I took between Tbilisi and Yerevan; the USSR might be about the last big area of the world where the default international lingua franca isn't English — yet, at least. It might be soon; Georgians' Russian competence is fairly widely reported to be falling very quickly.
I went to Venezuela with my friends when I was 17 for 4 weeks. I loved it! Venezuelan Spanish is arguably the most beautiful! Obviously there were moments when I had no idea what people were saying, but at the time I knew quite a lot of Spanish, and was able to muddle my way through. Then I graduated with great grades, and decided to treat myself with a gap year. I started out in Paris. My French level was pretty basic, but after a couple of months I improved a lot. I got a job working in an Art studio, for this great lady called Pascello, and I still visit her gallery to this day! Then I went on a charity trip to Burundi. My jumbled French got me through, and it was so great to support people in need! Currently I live in Lima, Peru, as an English teaching assistant. I have reached a level of fluency (kinda), and I'm pretty sure that without visiting so many cool places, I wouldn't be.