fix(skills): replace binary PPTX fixture with programmatic generator

[PratikWayase]

Pull Request

Description

This PR resolves the security and auditability concerns raised in #1135 regarding the committed binary minimal_test_fixture.pptx.

Changes Made:

1. Removed Opaque Binary: Deleted tests/fixtures/minimal_test_fixture.pptx to eliminate the risk of hidden macros, OLE objects, or malicious XML embedded in an unreviewable binary blob.
2. Programmatic Fixture Generation: Added logic in conftest.py to dynamically generate the minimal PPTX fixture at test runtime using python-pptx. Used lxml to manipulate the theme XML directly to ensure deterministic theme color resolution (dk1, accent1).
3. Roundtrip Validation: Added a new integration test test_generated_fixture_passes_validate_deck in test_extract_content_integration.py. This ensures the programmatically generated PPTX passes structural validation via validate_deck.py before extraction tests run, creating a closed-loop guarantee.

Benefits:

• Security: No more opaque binary blobs in the repository.
• Auditability: The exact contents of the test fixture are now fully visible and reviewable as standard Python code.
• Maintainability: The fixture can be easily updated in the future without needing external tools to regenerate a .pptx file.

Related Issue(s)

Fixes #1135

Type of Change

Select all that apply:

Code & Documentation:

• Bug fix (non-breaking change fixing an issue)
• New feature (non-breaking change adding functionality)
• Breaking change (fix or feature causing existing functionality to change)
• Documentation update

Infrastructure & Configuration:

• GitHub Actions workflow
• Linting configuration (markdown, PowerShell, etc.)
• Security configuration (Removes opaque binary blob from repository)
• DevContainer configuration
• Dependency update

AI Artifacts:

• Reviewed contribution with prompt-builder agent and addressed all feedback
• Copilot instructions (.github/instructions/*.instructions.md)
• Copilot prompt (.github/prompts/*.prompt.md)
• Copilot agent (.github/agents/*.agent.md)
• Copilot skill (.github/skills/*/SKILL.md)

Other:

• Script/automation (.ps1, .sh, .py)
• Other (please describe): Test infrastructure / Pytest fixtures

Testing

• Ran the full Python test suite locally using npm run test:py.
• Verified that all 758 PowerPoint tests pass, including the new test_generated_fixture_passes_validate_deck roundtrip validation test.
• Confirmed that the extraction tests correctly resolve the dynamically generated theme colors and metadata.
• (Note: The tts-voiceover test failures observed in the CI logs are pre-existing argparse issues in a completely separate skill and are unrelated to this PR).

Checklist

Required Checks

• Documentation is updated (if applicable)
• Files follow existing naming conventions
• Changes are backwards compatible (if applicable)
• Tests added for new functionality (if applicable)

Required Automated Checks

The following validation commands must pass before merging:

• Markdown linting: npm run lint:md
• Spell checking: npm run spell-check
• Frontmatter validation: npm run lint:frontmatter
• Skill structure validation: npm run validate:skills
• Link validation: npm run lint:md-links
• PowerShell analysis: npm run lint:ps
• Plugin freshness: npm run plugin:generate
• Docusaurus tests: npm run docs:test

Security Considerations

• This PR does not contain any sensitive or NDA information
• Any new dependencies have been reviewed for security issues (No new dependencies added; utilizes existing python-pptx and lxml)
• Security-related scripts follow the principle of least privilege

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.25%. Comparing base (8fc30bc) to head (da5f569).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2081      +/-   ##
==========================================
+ Coverage   81.61%   87.25%   +5.64%     
==========================================
  Files         130       86      -44     
  Lines       19489    11554    -7935     
  Branches       12        0      -12     
==========================================
- Hits        15906    10082    -5824     
+ Misses       3580     1472    -2108     
+ Partials        3        0       -3     

Flag	Coverage Δ
docusaurus	?
pester	85.93% <ø> (-0.02%)	⬇️
pytest	90.49% <ø> (+11.90%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.
see 46 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[katriendg]

Thanks for tackling this — replacing the opaque binary .pptx with a transparent, code-reviewable generator is a real security and auditability win, and the roundtrip validate_deck test is a nice closed-loop guarantee.
Note I reviewed the current version of the branch, though due to a merge conflict some of the comments may be stale. Please rebase and re-run the CI checks before merge.

Before merge, a few items: the two modified Python files currently fail the repo's ruff lint gate (npm run lint:py) with 13 errors — 9 trailing-whitespace blank lines, 2 lines over 88 chars, and 2 unsorted import blocks. Most are auto-fixable with ruff check --fix / ruff format. Beyond lint, please add type hints to the new helper functions, mark the new roundtrip test with @pytest.mark.integration (matching its sibling tests) and give it AAA structure, and reconsider the direct lxml import (it's only a transitive dep of python-pptx) and the author = "ChatGPT" fixture value. Details are in the inline review.

[katriendg]

Inline findings from the code review (the overall verdict remains Request changes from my earlier review). Each comment maps to a finding in the review summary.

[katriendg]

Thanks @PratikWayase for addressing the comments in this PR. Leaving one small comment which would be a nice one to add.
Also please ensure you rebase and then looking good.

addressed all feedback

[auyidi1]

New findings only. Excludes items already raised by katriendg/jkim323 and already addressed:

• ruff lint / trailing whitespace / line length / import ordering
• type hints on new helper functions
• @pytest.mark.integration marker on the roundtrip test
• author = "ChatGPT" → HVE Core Test Fixture
• direct lxml dependency thread (resolved in current head by adding lxml to
  pyproject.toml + uv.lock)

Each finding was verified by reproducing the generator and running validate_deck against the output.

Findings

1. [Medium] Roundtrip guarantee is weaker than advertised + load-bearing empty-notes line

• File: .github/skills/experimental/powerpoint/tests/test_extract_content_integration.py (L137)
• Related: .github/skills/experimental/powerpoint/tests/conftest.py (L151)

The roundtrip test asserts severity in ("info", "none"). Reproduction shows validate_deck
returns info (not none), because slide 2 has a notes slide with empty text
("Speaker notes present but empty").

That outcome depends entirely on conftest.py L151:

_ = slide2.notes_slide  # ensure notes part exists

Remove or reorder that line and slide 2 has no notes slide, check_speaker_notes emits a
warning, and the test fails — but the comment gives no hint the roundtrip test depends on it.

Recommendation:

• If the intent is a genuinely clean deck, give slide 2 real notes text and assert
  severity == "none".
• At minimum, make the coupling explicit in the comment so a future edit does not silently break
  the roundtrip test.

2. [Medium] set_color silently no-ops when a theme node is missing

• File: .github/skills/experimental/powerpoint/tests/conftest.py (L98–L108)

The two guards immediately above raise ValueError (missing theme_part at L86–L90, missing
clrScheme at L95–L96), but set_color does the opposite:

node = clr_scheme.find(f"a:{color_name}", ns)
if node is not None:
    ...   # no else — silently skips

dk1/accent1 are the source of truth for EXPECTED_FIXTURE["theme_colors"]
(test file L34–L37). If a future python-pptx default template renames or restructures these
nodes, generation silently produces the wrong theme and the failure surfaces as an opaque
assertion mismatch in the extraction tests rather than a clear error at the point of the bug.

Recommendation: Raise ValueError when node is None, consistent with the surrounding guards.

3. [Medium] Runtime generation couples fixtures to python-pptx's bundled default template

• Files: .github/skills/experimental/powerpoint/tests/test_extract_content_integration.py
  (L20, L28), .github/skills/experimental/powerpoint/pyproject.toml (L6)

Generating at test time makes the tests depend on python-pptx's bundled default.pptx staying
stable — layout names "Title Slide" / "Title and Content" and the clrScheme structure edited
in _set_theme_colors. The committed binary was self-contained; this trades that for a dependency
on upstream defaults. python-pptx is unpinned in pyproject.toml, so a contributor outside the
uv.lock pin could hit drift.

Recommendation: Add a minimum version constraint (or a short comment noting the tests assume the
bundled template's layout/theme names).