Increase Code Coverage for DataFrame module

[grundprinzip]

Increase Code Coverage for DataFrame module

[vnzhere]

Hi, I’m Vaniya, a 3rd year CS student exploring open-source contributions for GSoC 2026.

I’m interested in working on this issue to improve test coverage for the DataFrame module.
I’ve started exploring the repository and would love to take this up.

Please let me know if this issue is available or if there are any guidelines I should follow to get started.