Add unit test for tool/{util,ex,cmd} and tool/internal/{ast,setup}

[y1yang0]

Add comprehensive unit tests for common libraries such as tool/{util, ast, ex}, etc.

For some standalone utility functions within these packages, we hope to add more unit tests to improve coverage.

[nithinputhenveettil]

@y1yang0 : Would it be alright if I work on this? If so, could you please assign it to me?

[y1yang0]

@y1yang0 : Would it be alright if I work on this? If so, could you please assign it to me?

Welcome. Feel free to take over this

[nithinputhenveettil]

@y1yang0 : Thank you. I would appreciate it if you could assign this issue in my name.

[y1yang0]

@y1yang0 : Thank you. I would appreciate it if you could assign this issue in my name.

Sorry, but I currently don't have permission to edit issues. It might take me quite a long time to apply for access. You can consider yourself virtually assigned for now.

[ralf0131]

@nithinputhenveettil Are you still working on this issue？ If you like I can assign this issue it to you.

[ralf0131]

@y1yang0 I saw your pull request is link to this issue? Have this issue been resolved by your PR?

[nithinputhenveettil]

@ralf0131 : Yes, please. If this is still not resolved, please assign it to me. I will try to raise a PR within this week.

[y1yang0]

This issue haven't resolved yet. Assign to @nithinputhenveettil