Improve test coverage on pdb

[gaogaotiantian]

Feature or enhancement

Add more tests on pdb module

Pitch

The coverage on pdb module is poor - some of the commands are not tested at all. There are at least some low hanging fruits that we can do.

Linked PRs

• gh-102980: Add tests for pdf's display, alias and where commands #102981
• [3.11] gh-102980: Add tests for pdf's display, alias and where commands (GH-102981) #103016
• [3.10] gh-102980: Add tests for pdf's display, alias and where commands (GH-102981) #103017
• gh-102980: Redirect pdb interact command, add tests and improve docs #111194

[arhadthedev]

Should this issue be closed as done?

[gaogaotiantian]

Please don't close it yet. There are still some missing pieces and I need to wait for #102895 to do test on interact. I'll do more PRs related to this issue.