Its not a stringent process. All you should know is that you should have atleast a couple of months for IELTS/ TOEFL before you want to get admission into a college where such scores are a necessity for an application to be considered. Mostly all well reputed universities in Canada require this. And as Enfield said, its Strongly Reccommended since it verifies your command over the language, and for Visa, its all about such original/ verified documents that matters.