What are the sites for solving programming problems?

Question

PHP

Good day!
Please tell me, what are the sites where you can solve problems through assertions for the Unit test?
Those. in fact, unit tests are online.
Thanks :)

Answer 1

I remember exactly one site, there is a list of pre-prepared questions, and the answer should be CODE in one of the proposed languages.
You write the code, and inside the assertions.
But I lost the link to this site, but I can not find it in Google.
I also remember that he was not alone.
--
Found
www.codewars.com

Answer 2

exercism.io

Answer 3

There is such a cool thing - openserver. Install and test whatever you want. It is unlikely that someone will allow php scripts to be executed on their server as a service. Because:
- it's not safe
- nobody needs it