Add tests for CLI

[guptarohit]

We should have tests for CLI as well

[KarlHeitmann]

Do you have any idea on how to make the tests for CLI? I am quite new to go, I've done some testing on Rust, and I took a look at asciigraph_test.go file and understand how it works. But how can I test the for s.Scan() { ... } block on line 104? Do you have any resource or example I can take as source of inspiration? Would you like to test the flags passed to CLI are doing the right thing?

[guptarohit]

This would be tricky, possibly we have to redirect stdin & stdout. Redirect os.stdout to some in-memory buffer or temp file maybe? And similarly, pass out input test data to os.stdin.
Unfortunately atm I don't have any related resource for it, but if I find anything related to it I'll share here.
Yes, testing flags as well would be good idea.