cloud-init: T9172: add userdata command regression tests

[jeleel-muibi]

Proposed Commit Message

cloud-init: T9172: add userdata command regression tests

Add focused regression coverage for the VyOS-specific
vyos_config_commands handler. Exercise template discovery, supported
set/delete parsing, ordinary, multi, and nested tag-node updates, both
delete paths, and malformed-command skipping.

Use temporary template trees and a mocked ConfigTree interface so the
tests run without a VyOS image or installed template hierarchy.

Additional Context

Related task: T9172

This is a test-only change. It does not alter cloud-init runtime behavior,
dependencies, or configuration. The cases include the trailing multi-node
metadata behavior fixed in T3735 and the nested
tag-node preservation behavior fixed in T4895.

Test Steps

Validated with Python 3.10.20 and the repository-pinned tool versions:

python -m pytest -q tests/unittests/config/test_cc_vyos_userdata.py
9 passed

python -m black --check tests/unittests/config/test_cc_vyos_userdata.py
1 file would be left unchanged

python -m isort --check-only --diff tests/unittests/config/test_cc_vyos_userdata.py
python -m flake8 tests/unittests/config/test_cc_vyos_userdata.py
python -m mypy tests/unittests/config/test_cc_vyos_userdata.py
python -m pylint tests/unittests/config/test_cc_vyos_userdata.py
All passed; pylint rated the file 10.00/10.

python -m pytest -q tests/unittests \
  -k 'not test_get_script_folder_per_boot and not test_get_script_folder_per_instance and not test_get_script_folder_per_once'
3228 passed, 10 skipped, 3 deselected

The three host-dependent tests were deselected because they read
/etc/cloud/cloud.cfg.d/99-installer.cfg, which is not readable in the local
environment. An unfiltered run has only those three PermissionError
failures; none involves this test module.

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly (not applicable: test-only change)

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• tests/unittests/config/test_cc_vyos_userdata.py

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Files:

• tests/unittests/config/test_cc_vyos_userdata.py

🔍 Remote MCP vyos.dev

Relevant context

• Exact matching task: T9172 — “cloud-init: add regression coverage for vyos_config_commands”, status In progress, priority Low. Its acceptance criteria match this PR: unit tests only, mocked ConfigTree/template discovery, set/delete behavior, multi/tag handling, and malformed-command skipping.
• The task author confirmed they were actively working on the implementation and would submit a PR.
• Historical tag-node bug T4895 reported that repeated tag-node values were overwritten unless replace=False was used; this validates the nested tag-node preservation test.
• Historical multi-node bug T3735 involved template markers with trailing content/whitespace not matching a strict ^multi:$ pattern; this supports the trailing-metadata test.
• Separate resolved task T8185 documents a default-config path mismatch: cloud-init used /usr/share/vyos/config.boot.default, while flavor builds placed files under /opt/vyatta/etc/config.boot.default. Template/path fixtures should avoid assuming these locations are interchangeable.

🔇 Additional comments (1)

tests/unittests/config/test_cc_vyos_userdata.py (1)

3-186: LGTM!

---

📝 Walkthrough

Summary by CodeRabbit

• Tests
  • Added comprehensive coverage for VyOS userdata handling.
  • Verified template discovery and multi-node detection.
  • Added tests for parsing valid and malformed commands.
  • Covered setting, appending, preserving nested values, and deleting configuration nodes.
  • Confirmed valid commands are processed while malformed input is skipped.

Walkthrough

Changes

VyOS userdata tests

Layer / File(s)	Summary
Discovery and command parsing tests/unittests/config/test_cc_vyos_userdata.py	Tests template path discovery, multi-node detection, parsing of set and delete commands, and rejection of malformed input.
Command application and deletion tests/unittests/config/test_cc_vyos_userdata.py	Tests ordinary-node replacement, multi-node value appending, nested tag-node preservation, and deletion by value or path.
Command routing tests/unittests/config/test_cc_vyos_userdata.py	Tests application of valid commands and skipping of malformed commands.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the cloud-init component, task, and addition of userdata regression tests.
Description check	✅ Passed	The description accurately explains the VyOS regression tests, test scope, isolation approach, and validation results.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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