test(viewer): add dashboard and episode-viewer component tests

[WilliamBerryiii]

Description

Adds Vitest + React Testing Library coverage for the dataviewer frontend. Two stacked commits land together in this PR:

1. 5ac1235 — vitest/happy-dom test infrastructure plus dashboard, app-shell, and viewer-display component tests (33 tests across 5 files, plus ViewerDisplayControls). Closes test(dataviewer): add tests for dashboard components #219.
2. 1f6a15e — episode-viewer component tests (65 tests across 9 files), plus minor PlaybackControls aria-label additions to make controls testable. Closes #218A.

Total new coverage: 98 tests / 16 test files. Combined suite: 813/813 passing.

Closes #219
Closes #218A

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🏗️ Infrastructure change
• ♻️ Refactoring (no functional changes)

Test-only addition; closest fit is Refactoring. The single source change is non-functional aria-label additions on PlaybackControls.tsx.

Component(s) Affected

• infrastructure/ — Terraform, AKS, networking
• workflows/ — GitHub Actions CI/CD
• training/ — RL/IL training code
• docs/ — Documentation
• Other: data-management/viewer/frontend (test infrastructure + component tests)

Testing Performed

• Manual testing completed
• Unit tests added/updated
• Integration tests added/updated
• End-to-end tests verified

Test command:

cd data-management/viewer/frontend && npm run validate

Result: 81 test files / 813 tests passed in 28.64s · tsc clean · 0 lint errors / 39 pre-existing warnings.

Documentation Impact

• No documentation changes needed
• Documentation updated in this PR
• Documentation will be updated in a follow-up PR

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas (n/a — tests are self-describing)
• My changes generate no new warnings
• Any dependent changes have been merged and published

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Snapshot Warnings

⚠️: No snapshots were found for the head SHA 1f6a15e.

Ensure that dependencies are being submitted on PR branches and consider enabling retry-on-snapshot-warnings. See the documentation for more information and troubleshooting advice.

Scanned Files

None

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 68.95%. Comparing base (c809d2f) to head (1f6a15e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #595      +/-   ##
==========================================
+ Coverage   65.16%   68.95%   +3.79%     
==========================================
  Files         251      263      +12     
  Lines       15597    16812    +1215     
  Branches     2193     2302     +109     
==========================================
+ Hits        10164    11593    +1429     
+ Misses       5142     4925     -217     
- Partials      291      294       +3     

Flag	Coverage Δ		*Carryforward flag
pester	83.13% <ø> (ø)		Carriedforward from a7dd171
pytest-data-pipeline	100.00% <ø> (ø)		Carriedforward from a7dd171
pytest-dataviewer	66.97% <ø> (+0.05%)	⬆️	Carriedforward from a7dd171
pytest-dm-tools	100.00% <ø> (ø)		Carriedforward from a7dd171
pytest-evaluation	99.83% <ø> (?)
pytest-fuzz	4.91% <ø> (+0.01%)	⬆️	Carriedforward from a7dd171
pytest-inference	0.00% <ø> (ø)		Carriedforward from a7dd171
pytest-training	82.14% <ø> (ø)		Carriedforward from a7dd171
vitest	56.38% <100.00%> (+3.36%)	⬆️
vitest-app	56.38% <100.00%> (?)
vitest-components	56.38% <100.00%> (?)
vitest-features	56.38% <100.00%> (?)
vitest-lib	56.38% <100.00%> (?)
vitest-state	56.38% <100.00%> (?)

*This pull request uses carry forward flags. Click here to find out more.

Files with missing lines	Coverage Δ
...src/components/episode-viewer/PlaybackControls.tsx	100.00% <100.00%> (+42.85%)	⬆️

... and 38 files with indirect coverage changes

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[katriendg]

✅ Approved — Solid test coverage addition

98 new tests across 16 files with no regressions detected. The globals: false change is safe (all existing tests already import explicitly from vitest), aria-label additions improve both testability and accessibility, and the Response-based mock refactors are a strict improvement.

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💡 Minor items — address at your discretion

These are all non-blocking style observations; feel free to ignore or address in follow-up:

1. Redundant cleanup() calls

setup.ts now registers a global afterEach(() => { cleanup() }), but 6 test files (StarRating, ActivityFeed, AnnotatorLeaderboard, IssuesSummary, ProgressOverview, QualityDashboard, RatingDistribution) still call cleanup() in their own afterEach. Harmless duplication — could remove the per-file ones for consistency.

2. Fragile CSS-class selectors

A few tests query by Tailwind utility classes (.animate-pulse, .font-medium, span.truncate.font-medium). These will break silently if class names change. Prefer role, aria-label, or data-testid where possible.

3. as never type casts on store mocks

Timeline.test.tsx, VideoPlayer.test.tsx, and TrajectoryPlot.test.tsx use as never to silence type mismatches on mock returns. A more precise cast (e.g., as ReturnType<typeof usePlaybackControls>) would preserve compile-time validation.

4. jsonResponse duplication

test-utils.tsx exports a nice jsonResponse helper, but api-client.test.ts and use-joint-config.test.ts maintain their own local versions. Could consolidate to one source.

5. Non-null assertion after expect guard (Timeline.test.tsx ~L183)

expect(playhead).not.toBeNull()
expect(playhead!.style.left).toBe('50%')

An if (playhead) narrowing or optional chaining would be more idiomatic TypeScript.

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None of the above affect correctness or test reliability. Nice work on the coverage push! 🎉