feat(r): add test coverage hooks for R testthat convention

[sims1253]

Summary

Adds test coverage detection support for R projects following the standard testthat convention.

What this does

• Maps tests/testthat/test-*.R → R/*.R source files
• Recognizes all expect_* assertion patterns from testthat
• Handles library()/require() imports in test files for dependency resolution
• Strips R comments while preserving string literals

Changes

 desloppify/languages/r/__init__.py            |   2 +
 desloppify/languages/r/test_coverage.py       | 167 ++++++++++++++++++++
 desloppify/languages/r/tests/test_r_test_coverage.py | 115 ++++++++++++++
 3 files changed, 284 insertions(+)

Testing

All 19 tests pass. The module follows the same structure as existing R plugins (test coverage modules for Python, JavaScript, etc.).

This is a focused, standalone addition that does not modify any existing behavior — it only adds the test_coverage_module hook to the R language plugin.

[peteromallet]

Thank you @sims1253 for this contribution! Cherry-picked with a small adjustment (fixed strip_test_markers to return the bare basename) as commit 72a2b34. Closing in favor of the merged commit.

[peteromallet]

Thanks for the PR. I accepted the R test coverage hook feature with two conditions around redundant assertion patterns and strip_test_markers() behavior.

Decision: fixed in the current tree. The R test coverage hooks are already present via prior commits 72a2b343 and c1bce81f; I verified that strip_test_markers() now returns the basename form expected by the shared coverage engine. I also simplified the assertion patterns in 3d92333f so the list uses the expect_* catch-all plus verify_output, avoiding redundant specific expect_* entries.

Validation run:

• PYENV_VERSION=3.11.11 python -m pytest desloppify/languages/r/tests/test_r_test_coverage.py desloppify/languages/r/tests/test_r_air.py desloppify/tests/detectors/coverage/test_test_coverage.py -q

This PR was already closed, so I am leaving this note as the final decision record.

[peteromallet]

Thanks for the contribution. This is included in v1.0: https://github.com/peteromallet/desloppify/releases/tag/v1.0