[DocDB] Add unit tests to cover yb-admin flush_table and compact_table output

[arybochkin]

Jira Link: DB-18273

Description

Add unit tests (yb-admin-test) to check output of yb-admin has expected format. The following commands (with all the set of input args should be covered): compact_table, compact_table_by_id, flush_table, flush_table_by_id.

Issue Type

kind/enhancement

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[kenju]

Hi @arybochkin 👋🏻 I'm working on yb-admin in a different context (#28733) and am interested in picking this up as a side quest.

Add unit tests (yb-admin-test) to check output of yb-admin has expected format. The following commands (with all the set of input args should be covered): compact_table, compact_table_by_id, flush_table, flush_table_by_id.

Before I go deep, I made a quick changes here kenju@cd4fcdd to see if I'm in a right direction regarding the original requirement. If this commit looks good to you, I'm happy to expand more test cases on verifying command output for compact_table, compact_table_by_id, flush_table, flush_table_by_id. Would love to get your feedback.

[kenju]

As a first step, I've raised a quick PR for flush_table #28804, can I get your review when you're around?

[arybochkin]

Hey @kenju, your changes and overall direction look good to me. A couple of suggestions:

1. It’s better to keep a smaller number of tests per command for this particular task. If possible, combine smaller tests into a single larger one (ideally, one test per command -- though that might not be fully achievable).
2. Make sure to check the exact output format, including spaces, dots, commas, etc.
3. Make sure to cover scenarios like command timeouts, etc.

Thank you!