fix(trainer): validate polling_interval in wait_for_job_status

[HarshPopat23]

What this PR does / why we need it:

Adds input validation to TrainerClient.wait_for_job_status() to reject

non-positive polling_interval values before delegating to the backend.

Previously, passing polling_interval=0 could cause a CPU busy-loop

(time.sleep(0) in a tight polling loop), and negative values raised a

cryptic stdlib ValueError from deep inside time.sleep() with no

context about which argument was invalid.

Which issue(s) this PR fixes:

Fixes #550

Checklist:

• Docs included if any changes are user facing (docstring already documented ValueError: The input values are incorrect. — no change needed)

[google-oss-prow]

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[Copilot]

Pull request overview

Adds early input validation to the user-facing TrainerClient.wait_for_job_status() API to reject invalid polling_interval values before delegating to the selected backend, and adds a unit test to cover the new validation behavior.

Changes:

• Added a guard in TrainerClient.wait_for_job_status() to raise ValueError when polling_interval <= 0.
• Added unit tests verifying ValueError is raised for polling_interval of 0 and -5.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
kubeflow/trainer/api/trainer_client.py	Adds polling_interval validation before calling backend wait_for_job_status().
kubeflow/trainer/api/trainer_client_test.py	Adds a unit test ensuring invalid polling_interval values raise ValueError.

[andreyvelich]

/ok-to-test
/retest

[Goku2099]

Small naming suggestion: since this helper validates both polling_interval and timeout specifically for wait_for_job_status, would something like validate_wait_for_job_status_args() (or ..._params()) make its purpose a bit clearer?
Not a blocker, just a readability suggestion.

[HarshPopat23]

Small naming suggestion: since this helper validates both polling_interval and timeout specifically for wait_for_job_status, would something like validate_wait_for_job_status_args() (or ..._params()) make its purpose a bit clearer? Not a blocker, just a readability suggestion.

Hi @Goku2099, thank you for taking the time to review my PR and for the suggestion! I actually used this function name based on a recommendation from @andreyvelich. If they agree that validate_wait_for_job_status_args() (or a similar name) is more appropriate, I'd be happy to update it. Thanks again for the helpful feedback!