Though I haven't checked all the countries in the world, I'm sure that many of those that respect themselves require their prospective citizens to have a test of their respective national languages and show a sufficiently high level of practical knowledge of these languages. I know as a fact that the Russian Federation, for example, has such a state-run examination called тестирование по русскому языку иностранных граждан.
Israel is one of the exceptions to this. According to its Law of Return, every Jewish person and those who have at least one Jewish grandparent, including those who are therefore halakhically non-Jewish, are eligible for Israeli citizenship upon their arrivial to the country without proving their proficiency in Hebrew. This law was enacted to offer a safe refuge to everyone who was persecuted according to the so-called Nuremberg Laws, which led to the Holocaust.
I don't know if this is realistic, but personally I would like to see this law reformed so that every new applicant may receive Israeli citizenship only after proving his or her proficiency in Hebrew as well as basic cultural literacy in Judaism and Israel.
Though such a legal requirement doesn't exist yet, many new citizens learn Hebrew quite well, at least in speaking, including those from the Russian Federation who don't know any other foreign language and even if they immigrated to Israel after the age of retirement.
There is one noticeable group of people who don't take the trouble of learning Hebrew at all and continue speaking to everyone here in the language of the coutry of their origin as if they were still living there. Actually, they are still living there, at least in their mind. I wish I were wrong, but the more people of this group I meet, the more convinced I'm that they waited to immigrate here until after retirement in their country of origin in order to take from two countries without giving to their new country. I would even call this linguistic arrogance, which seems to be part of the overall arrogance of their country of origin I witness in many other areas of life.
Unfortunately, many native speakers of Hebrew in Israel seem to "collaborate" on this. They willingly give up Hebrew in favor of the native language of these immigrants. Both of them seem to assume that the whole world speaks this language. Though it's one of the languages I use very actively, I don't like to be spoken to in it by those who have an apparent Hebrew accent as this seems to be the mentality of the colonized who don't respect their native language (and national culture).