Fixes for SNMP Tests Flakiness

[agadia-cisco]

Description of PR

Summary: The PR contains changes to snmp_helpers.py which checks whether snmp-subagent process is up or not before proceeding in the test. Accordingly all the snmp tests were updated to accommodate the change. This fixes the SNMP tests failures due to information not gathered in get_snmp_facts.

Fixes # (issue)

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Back port request

• 201911
• 202012
• 202205
• 202305
• 202311
• 202405

Approach

What is the motivation for this PR?

It has been observed that without snmp-subagent being up, SNMP tests proceeds to execution causing TC failures because snmp_facts isn't able to capture the device information.

How did you do it?

Check was added in snmp_helpers ensuring that snmp-subagent is up before calling snmp_facts. All TCs were updated with the change.

How did you verify/test it?

Had run the changes on 202405 image installed in T0 device & tests passed.

[mssonicbld]

The pre-commit check detected issues in the files touched by this pull request.
The pre-commit check is a mandatory check, please fix detected issues.

Detailed pre-commit check results:
trim trailing whitespace.................................................Passed
fix end of files.........................................................Passed
check yaml...........................................(no files to check)Skipped
check for added large files..............................................Passed
check python ast.........................................................Passed
flake8...................................................................Failed
- hook id: flake8
- exit code: 1

tests/common/helpers/snmp_helpers.py:37:121: E501 line too long (129 > 120 characters)
tests/common/helpers/snmp_helpers.py:38:21: E128 continuation line under-indented for visual indent

flake8...............................................(no files to check)Skipped
check conditional mark sort..........................(no files to check)Skipped

To run the pre-commit checks locally, you can follow below steps:

1. Ensure that default python is python3. In sonic-mgmt docker container, default python is python2. You can run
   the check by activating the python3 virtual environment in sonic-mgmt docker container or outside of sonic-mgmt
   docker container.
2. Ensure that the pre-commit package is installed:

sudo pip install pre-commit

3. Go to repository root folder
4. Install the pre-commit hooks:

pre-commit install

5. Use pre-commit to check staged file:

pre-commit

6. Alternatively, you can check committed files using:

pre-commit run --from-ref <commit_id> --to-ref <commit_id>

[vperumal]

@abdosi @SuvarnaMeenakshi @yejianquan - Can you help review and merge this PR

[yejianquan]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[yejianquan]

@agadia-cisco @vperumal , added comments, thanks

[yejianquan]

@agadia-cisco
Saw you test result in the collapsed comment, next time please paste the test result in the PR description,
And for the 2 failures in the output,
I believe they were here before your change and not related to your change, right?

[agadia-cisco]

@agadia-cisco Saw you test result in the collapsed comment, next time please paste the test result in the PR description, And for the 2 failures in the output, I believe they were here before your change and not related to your change, right?

Both the failures are not related to my change & were seen before my changes too.

• snmp/test_snmp_psu.py::test_snmp_numpsu failure, PR 14860 was already raised & it was merged today.
• snmp/test_snmp_queue_counters.py::test_snmp_queue_counters failure, we are looking into the issue.

[yejianquan]

LGTM

[mssonicbld]

Cherry-pick PR to 202405: #15269