[Copilot]

Improves test coverage, adds a coverage CI job and documents the package for contributors and agents. R was not available in the authoring environment, so none of this has been run. Please run the tests and the new workflow before merging.

• Tests (tests/testthat/test-maglab-magmap.R)
  • The existing suite covers most plotting functions but never tests maglab or magmap directly, so I added those.
  • maglab tests cover the return structure, trim, log label placement, and the error when usemultloc is used without log=TRUE.
  • magmap tests cover the output range and that flip=TRUE inverts the mapping.
  • Expectations come from reading the code and haven't been checked against R, so a failure may be a wrong expectation rather than a bug.
  • magband, magproj, magMWdust and magimageRGB still appear to lack direct tests. I chose targets by reading the test files, not from a coverage report.
• CI (.github/workflows/test-coverage.yaml)
  • New covr job on Ubuntu, run on push and PR to main/master. It prints coverage and writes a Cobertura report. It does not upload results or enforce a threshold.
  • R-CMD-check.yaml is unchanged.
• AGENTS.md
  • Covers the package layout, including exportPattern exports and the hand-written man/ Rd files.
  • Covers the ParmOff dependency, test and check commands, the null-device convention for plotting tests, CI, and style.

[Copilot]

🔵 Needs a closer look

The requested pre-merge R tests and coverage workflow have not been executed, leaving runtime behavior and CI dependency installation unverified.

No open issues 🎉

What changed in this PR

Adds direct tests for maglab and magmap, coverage reporting in CI, and contributor guidance for the magicaxis R package.

Changes:

• Tests label structure, trimming, logarithmic placement, invalid options, mapping bounds, and flipped mappings.
• Adds an Ubuntu coverage workflow that prints coverage and generates a Cobertura report without uploading results or enforcing a threshold.
• Documents package layout, dependencies, development commands, and testing conventions.

The new tests and workflow remain unverified at runtime.

File	Description
tests/​testthat/​test-maglab-magmap.R	Adds computational tests for label generation and numeric mapping.
AGENTS.md	Documents contributor and agent guidance.
.github/​workflows/​test-coverage.yaml	Adds coverage reporting for pushes and pull requests targeting main or master.

_{Review effort: Balanced}