If you don't need to take a language test for citizenship or a job, I think language tests are not necessary to prove to yourself that you know your target language well. If you've only been learning your target language for a few years, that might be too early to take a test. Why? Because you may have to study for it.
Me personally, I would only take a language test if it'll be like a walk in the park taking it. This means that my language skills are so well-developed by doing activities like reading, watching movies/videos, or listening to audio books. Think of a college English major taking an English test for 3rd graders. That test will be so easy that the test feels like something you're doing to past the time instead of a huge event.
My target language is Spanish as most of you know who have been reading my posts. I read every day and after each book I read, my reading skills and vocabulary increases immensely. However, I wouldn't say I'm ready to take a language test because I still use my Kindle eReader so I can translate on the fly. When I listen to audio books, I still can't follow the story, but I will hear words here and there that I recognize. As I write this, it will be 3 years in August 2026 of me consistently learning Spanish on a daily basis. I still feel like I have a long way to go. I'm better than I was over 2 years ago and better than I was last year.
I take this approach because my target language never gets treated like a chore. I read as much as a I want… even if that's only a few sentences a day.
There's a video by a woman by the name of Beniko Mason who uses stories to teach languages. She was speaking to a Japanese woman who took the TOEIC (Test of English for International Communication) because her job required it. She got a really high score on the test not because she studied, but because she did a lot of pleasure reading in English. She actually said she never studied for it.
In my opinion, I think all language learners should pick up the joy of reading. Even if it's a few pages at a time. I'm gonna show you how powerful this is.
There are a dozen ways to say one thing. The closer you get to that dozen, the more extensive your vocabulary is. If you're not a big reader, you will see a lot of unfamiliar words in everything you read. However, if you do read a lot, a lot of uncommon words are more "common" to you. When you do take these tests without studying, you will look like a deer caught in headlights. If you study, there will be words you remember from studying and other words you may have forgotten. When you read a lot, the language gets cemented in your brain. Being that you encounter a lot of uncommon words regularly through reading, you will notice that you know more than the people who have studied because their knowledge of these words or phrases are stored in their short-term memory, but you organically remember the words and phrases because you've seen them so many times in different books and mediums.
To help you understand this better, let's say you read a book written for a 3rd grader where you know 100% of the words, phrases, grammar, sentence structure, and anything that has to do with the language. Give that same book to a second grader, they may be confused because there will be a lot of unfamiliar words and grammar-related things in the reading material.
This is why I think people should do activities to boost their vocabulary and improve the command of their target language so they'll pass the test organically instead of cram the material of what's gonna be on the test.
Picture this for a moment. From age 6 all the way up to age 18, you've been reading for pleasure. As your command of the English language improved you moved on to more advanced books with a more sophisticated vocabulary. Over 12 years, you've been reading so much that you can even read at a Freshman college level while you're still a senior in High school. Every type of math you learn, you do about 20–100 problems a day through some type of math game. You've been doing all of this over a 12 year period and it's all out of pleasure, not a chore. When you take the SATs, how well do you think you'll do? While everyone has been prepping and studying, you've cemented the English language and maths in our brain at a higher level that the SATs will feel like just another activity to pass the time. You may even finish before the rest of your classmates
In the realm of language learning, do activities that sharpen and improve your langauge skills over time, don't study and turn the language into a chore. The test will just be confirmation that you know what you already knew all this time when you pass, not something that makes you feel good about yourself because you've studied for this test for hours just to pass it.