Subject: sonic-mgmt: fix tagged-arp test for large topos

[ccroy-arista]

Description of PR

Summary: For large topos, i.e. those with a large number of interfaces, there exists a likely possibility that show arp will not be up to date when the call is made.

Try the show arp command again before moving on.

Type of change

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

Back port request

• [ ] 202012
• [ ] 202205
• [ ] 202305
• [x] 202311
• [x] 202405

Approach

What is the motivation for this PR?

Fix test failure for topos with large number of interfaces.

How did you do it?

Wrapped the arp entry check in a wait_until, which will attempt the show arp command a few times on a given interface before failing.

How did you verify/test it?

Ran the offending test (tests/arp/test_tagged_arp.py) several times and confirmed that failure was not observed and that the test passed every time.

Any platform specific information?

Verified on Arista-7060X6-64PE-256x200G.

[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/arp/test_tagged_arp.py:91:1: E302 expected 2 blank lines, found 1
tests/arp/test_tagged_arp.py:92:27: E703 statement ends with a semicolon
tests/arp/test_tagged_arp.py:122:20: E703 statement ends with a semicolon
tests/arp/test_tagged_arp.py:128:1: E302 expected 2 blank lines, found 1
tests/arp/test_tagged_arp.py:159:121: E501 line too long (126 > 120 characters)

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>

[ccroy-arista]

Checking pre-commit...

[Janetxxx]

@ccroy-arista I cherry-picked this PR and ran the test, but received an AssertionError: Expected 10 entries, but 0 found. It seems ARP packets have not been received by the DUT for some reason. I'll ping you offline to discuss it further. Thanks.

[StormLiangMS]

hi @Janetxxx do we still see failure with internal runs?

[Janetxxx]

hi @Janetxxx do we still see failure with internal runs?

Hi @StormLiangMS , It still failed in our internal run, I'll have a look in the next coming days.

[r12f]

since the issue on our side is caused by different things from the issue being fixed here, let's get this merged, because eventually we will hit this anyway.

[StormLiangMS]

hi @yxieca need cherry pick.

[mssonicbld]

Cherry-pick PR to 202311: https://github.com/sonic-net/sonic-mgmt/pull/15023

[mssonicbld]

Cherry-pick PR to 202405: https://github.com/sonic-net/sonic-mgmt/pull/15024