fix: display errors when schema validation fails

[chronicc]

When using the ansible native configuration I get a "Failed to validate" error without further notice about what is wrong.

extensions/molecule/config.yml

---
ansible:
  executor:
    args:
      ansible_playbook:
        - --inventory=${MOLECULE_SCENARIO_DIRECTORY}/../inventory/hosts.yml
    env:
      ANSIBLE_COLLECTIONS_PATHS: ${MOLECULE_SCENARIO_DIRECTORY}/../../..
      ANSIBLE_FORCE_COLOR: true
      ANSIBLE_HOST_KEY_CHECKING: false

scenario:
  test_sequence:
    - prepare
    - converge
    - verify
    - idempotence
    - verify
    - cleanup

shared_state: true

extensions/molecule/default/molecule.yml

---
scenario:
  test_sequence:
    - create
    - destroy

Shell Output

❯ uv run molecule create
INFO     Found config file /home/chronicc/git/chronicc/ansible-collection-toolchain/extensions/molecule/config.yml
INFO     Collection 'chronicc.toolchain' detected.
INFO     Scenarios will be used from 'extensions/molecule'
WARNING  default ➜ config: The scenario config file ('/home/chronicc/git/chronicc/ansible-collection-toolchain/extensions/molecule/default/molecule.yml') has been modified since the scenario was created. If recent changes are important, reset the scenario with 'molecule destroy' to clean up created items or 'molecule reset' to clear current configuration.
ERROR    Failed to validate /home/chronicc/git/chronicc/ansible-collection-toolchain/extensions/molecule/default/molecule.yml

Environment

# Python
❯ uv run python -V
Python 3.13.7

# Python Dependencies
❯ uv pip freeze
ansible-builder==3.1.1
ansible-compat==25.12.1
ansible-core==2.19.7
ansible-creator==26.3.2
ansible-dev-environment==26.2.0
ansible-dev-tools==26.3.1
ansible-lint==26.3.0
ansible-navigator==26.1.3
ansible-runner==2.4.3
ansible-sign==0.1.5
attrs==26.1.0
bindep==2.14.0
black==26.3.1
bracex==2.6
cachetools==7.0.5
cffi==2.0.0
click==8.3.1
colorama==0.4.6
cryptography==46.0.5
distlib==0.4.0
distro==1.9.0
enrich==1.2.7
execnet==2.1.2
filelock==3.25.2
iniconfig==2.3.0
jinja2==3.1.6
jmespath==1.1.0
jsonschema==4.26.0
jsonschema-specifications==2025.9.1
lockfile==0.12.2
markdown-it-py==4.0.0
markupsafe==3.0.3
mdurl==0.1.2
molecule==26.3.0
mypy-extensions==1.1.0
onigurumacffi==1.5.0
packaging==26.0
parsley==1.3
pathspec==1.0.4
pbr==7.0.3
pexpect==4.9.0
platformdirs==4.9.4
pluggy==1.6.0
ptyprocess==0.7.0
pycparser==3.0
pygments==2.19.2
pyproject-api==1.10.0
pytest==9.0.2
pytest-ansible==26.2.0
pytest-xdist==3.8.0
python-daemon==3.1.2
python-discovery==1.2.0
python-gnupg==0.5.6
pytokens==0.4.1
pyyaml==6.0.3
referencing==0.37.0
resolvelib==1.2.1
rich==14.3.3
rpds-py==0.30.0
ruamel-yaml==0.19.1
ruamel-yaml-clib==0.2.15
ruff==0.15.7
setuptools==82.0.1
subprocess-tee==0.4.2
tomli-w==1.2.0
tox==4.50.3
tox-ansible==26.3.0
typing-extensions==4.15.0
tzdata==2025.3
virtualenv==21.2.0
wcmatch==10.1
yamllint==1.38.0

After fix

❯ uv run molecule create
INFO     Found config file /home/chronicc/git/chronicc/ansible-collection-toolchain/extensions/molecule/config.yml
INFO     Collection 'chronicc.toolchain' detected.
INFO     Scenarios will be used from 'extensions/molecule'
WARNING  default ➜ config: The scenario config file ('/home/chronicc/git/chronicc/ansible-collection-toolchain/extensions/molecule/default/molecule.yml') has been modified since the scenario was created. If recent changes are important, reset the scenario with 'molecule destroy' to clean up created items or 'molecule reset' to clear current configuration.
ERROR    Failed to validate /home/chronicc/git/chronicc/ansible-collection-toolchain/extensions/molecule/default/molecule.yml

Additional properties are not allowed ('env' was unexpected)

Summary by CodeRabbit

• Bug Fixes

  • Improved validation error messages by displaying each issue on a separate line for easier reading.
  • Validation failures are now formatted more clearly when multiple issues are reported, making it easier to identify and resolve individual problems.

• Tests

  • Updated validation coverage to reflect the improved handling and presentation of multiple validation errors.

[chronicc]

Apparently the code uses a list to handle errors but the tests did not reflect that. Hence I updated the tests also.

[ssbarnea]

@chronicc Please sign the commit, we cannot merge PRs without it now.

[chronicc]

@ssbarnea Signed :)

[shatakshiiii]

Hi @chronicc , some of the tests are failing please take a look

moving this to draft until CI is back to green.

[shvenkat-rh]

@chronicc any updates on this draft?

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Configuration used: Organization UI

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Plan: Advanced

Run ID: b8dbfc40-f89a-4b7a-8432-b3c7f15cf444

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Reviewing files that changed from the base of the PR and between 500f645 and 0ad369b.

📒 Files selected for processing (2)

• src/molecule/config.py
• tests/unit/test_config.py

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---

📝 Walkthrough

Walkthrough

The validation failure message now displays each error on a separate line. The related unit test now supplies validation errors as a list.

Changes

Validation Error Formatting

Layer / File(s)	Summary
Format validation errors src/molecule/config.py, tests/unit/test_config.py	Config._validate joins validation errors with newline separators. The unit test mocks the validator with a list of errors.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Bug fix

Suggested reviewers: cidrblock

Merge Risk: ⚪ Minimal · up to 0ad36

The PR improves schema validation messages without introducing a supported current-head risk.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the fix to display schema validation errors.
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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