I was working on a library called WhatsAlgo and needed 2 types of functionality:

• generator: generates a bunch of test cases and creates one or more input files
• validator: takes the solution file (could be in C++, Python, or other languages) and verifies it on each of the generated input files

This got me wondering, how do people generate test cases? I came across 2 popular platforms:

• testlib by MikeMirzayanov
• tokilib by fushar

Are these the platforms used by the testers on CodeForces?

What about other platforms like AtCoder, HackerRank, LeetCode, or even Google?

I'd appreciate it if someone shed some light on this as it would help me a lot. Thank you all for your help!