[dualtor][test gap] Add testcases to cover the faulty ycable

[lolyu]

Description of PR

Summary:
Fixes # (issue)

Type of change

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

Back port request

• 202012
• 202205
• 202305
• 202311
• 202405

Approach

What is the motivation for this PR?

To fix test gap: #12311

Signed-off-by: Longxiang Lyu lolv@microsoft.com

How did you do it?

To simulate a faulty ycabled, a templated y_cable_simulated.py is used to replace the original ycable driver.
With the faulty ycable driver, two testcases are added:

1. add test_switchover_probe_unknown to verify dualtor could toggle as expected even ycabled returns mux probe unknown.
2. add test_switchover_peer_link_down to verify dualtor could toggle as expected even ycabled returns peer link down.

How did you verify/test it?

dualtor/test_switchover_faulty_ycable.py::test_switchover_probe_unknown PASSED                                                                                                                                                                       [ 50%]
dualtor/test_switchover_faulty_ycable.py::test_switchover_peer_link_down PASSED                                                                                                                                                                      [100%]
======================================================================================================== 2 passed, 2 warnings in 411.34s (0:06:51) =========================================================================================================

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation

[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.................................................Failed
- hook id: trailing-whitespace
- exit code: 1
- files were modified by this hook

Fixing tests/dualtor/test_switchover_faulty_ycable.py

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/dualtor/test_switchover_faulty_ycable.py:5:1: F401 'ipaddress' imported but unused
tests/dualtor/test_switchover_faulty_ycable.py:7:1: F811 redefinition of unused 'pytest' from line 4
tests/dualtor/test_switchover_faulty_ycable.py:10:1: F811 redefinition of unused 'logging' from line 3
tests/dualtor/test_switchover_faulty_ycable.py:23:1: E303 too many blank lines (3)
tests/dualtor/test_switchover_faulty_ycable.py:46:121: E501 line too long (153 > 120 characters)
...
[truncated extra lines, please run pre-commit locally to view full check results]

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>

[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.................................................Failed
- hook id: trailing-whitespace
- exit code: 1
- files were modified by this hook

Fixing tests/dualtor/test_switchover_faulty_ycable.py

fix end of files.........................................................Passed
check yaml...........................................(no files to check)Skipped
check for added large files..............................................Passed
check python ast.........................................................Passed
flake8...................................................................Passed
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>