Publish Pester test and coverage results in GitHub UI

[blindzero]

Problem Statement

In CI, Pester currently generates:

• Test results: artifacts/test-results.xml (NUnitXml)
• Coverage results: artifacts/coverage.xml (JaCoCo XML)

These files are uploaded as GitHub Actions artifacts, but GitHub does not render them in a TeamCity-like way. Consumers must download ZIP artifacts to inspect failures/coverage, which slows reviews and reduces visibility in PRs and workflow runs.

Proposed Solution

Enhance the CI workflow to publish Pester test and coverage results in GitHub’s UI:

1. Publish test results as a GitHub Check

   • Use a test report action that supports NUnit XML (e.g. dorny/test-reporter)
   • Run with if: always() so failures still produce a report
   • Ensure required permissions for checks (e.g. checks: write)

2. Publish coverage results in GitHub UI

   • Keep the existing Pester coverage output format (JaCoCo XML) and use a JaCoCo reporter action to create a Check and/or Job Summary.
   • Additionally write a compact coverage summary into $GITHUB_STEP_SUMMARY (percentage + covered/total lines if available).

3. Fork/PR safety

   • If Check creation is restricted for PRs from forks, gate reporting appropriately (e.g. only on non-fork PRs), or adopt a workflow_run pattern to render reports from uploaded artifacts.

Acceptance Criteria

• A PR shows a Tests check with pass/fail and a readable list of failing tests (no artifact download required).
• The workflow run shows a readable coverage summary (check and/or run summary).
• Reports are produced even when tests fail (if: always()).
• The solution works for typical contribution flows and does not require external services (Codecov/Coveralls optional, not required).

Alternatives Considered

• Artifacts only (status quo): simplest, but reviewers must download ZIPs and manually inspect XML.
• External coverage services (Codecov/Coveralls): great UX, but adds third-party dependency and configuration overhead.
• Convert coverage format to Cobertura: would unlock more generic coverage summary actions, but requires changing Pester coverage output configuration.

Impact

• Does this affect existing workflows?
  • Only CI reporting; no runtime module behavior changes.
• Any backward compatibility concerns?
  • None for module consumers.
  • CI permissions might need adjustment (checks: write), and fork PR behavior must be handled carefully.

Additional Context

• Current CI already produces and uploads:
  • artifacts/test-results.xml (NUnitXml)
  • artifacts/coverage.xml (JaCoCo XML)
• Desired outcome: reviewers can see failures/coverage directly in GitHub PR checks and/or workflow summaries, similar to other CI systems.