Add tests

[Xabadu]

Reference: https://code.visualstudio.com/api/working-with-extensions/testing-extension

[hacky1997]

I want to work on this. Could you please change the label to in progress?

[Xabadu]

@hacky1997 you got it! Thank you for taking this! - Feel free to let us know if you have any questions or comments.

[theREALaltoid]

I'd like to add some test as well. Would it be possible to merge @hacky1997 's tests with my tests?

[Xabadu]

Hi @theREALaltoid, thanks for reaching out! I think it's up to @hacky1997 and the current work he's gonna be doing with the tests.

@hacky1997 is your current work with test planning to cover all cases, or is there some work that can be divided that @theREALaltoid can help with?