r-package

name	r-package
description	R package development with devtools, testthat, and roxygen2. Use when the user is working on an R package, running tests, writing documentation, or building package infrastructure.
metadata	{"author":"Simon P. Couch (@simonpcouch)","version":"1.2"}

R package development

⚠️ Project overrides (this repo's house style wins over the upstream skill below):

• Pipe: use %>% (magrittr), not |>. This overrides the "Coding" guidance below — see the r-style rule.
• Error/warning tests: use expect_error() / expect_warning() (or expect_snapshot() only when you specifically want to capture full message text), not a blanket expect_snapshot(error = TRUE). This overrides the "Testing" guidance below.
• Formatting: air format is optional; follow the tidyverse style in the r-style rule. Do not introduce it as a required step.
• Everything else in this skill (devtools commands, test layout in tests/testthat/, roxygen workflow) applies as written.

Key commands

# Run code in the package
Rscript -e "devtools::load_all(); code"

# Run all tests
Rscript -e "devtools::test()"

# Run all tests for files starting with {name}
Rscript -e "devtools::test(filter = '^{name}')"

# Run all tests for R/{name}.R
Rscript -e "devtools::test_active_file('R/{name}.R')"

# Run a single test "blah" for R/{name}.R
Rscript -e "devtools::test_active_file('R/{name}.R', desc = 'blah')"

# Redocument the package
Rscript -e "devtools::document()"

# Check pkgdown documentation
Rscript -e "pkgdown::check_pkgdown()"

# Check the package with R CMD check
Rscript -e "devtools::check()"

# Format code
air format .

Coding

• Always run air format . after generating code.
• Use the base pipe operator (|>) not the magrittr pipe (%>%).
• Use \() ... for single-line anonymous functions. For all other cases, use function() {...}.

Testing

• Tests for R/{name}.R go in tests/testthat/test-{name}.R.
• All new code should have an accompanying test.
• If there are existing tests, place new tests next to similar existing tests.
• Strive to keep tests minimal with few comments.
• Avoid expect_true() and expect_false() in favour of a specific expectation which will give a better failure message.
• When testing errors and warnings, don't use expect_error() or expect_warning(). Instead, use expect_snapshot(error = TRUE) for errors and expect_snapshot() for warnings because these allow the user to review the full text of the output.

Documentation

• Every user-facing function should be exported and have roxygen2 documentation.
• Wrap roxygen comments at 80 characters.
• Internal functions should not have roxygen documentation.
• Whenever you add a new (non-internal) documentation topic, also add the topic to _pkgdown.yml.
• Always re-document the package after changing a roxygen2 comment.
• Use pkgdown::check_pkgdown() to check that all topics are included in the reference index.

NEWS.md

• Every user-facing change should be given a bullet in NEWS.md. Do not add bullets for small documentation changes or internal refactorings.
• Each bullet should briefly describe the change to the end user.
• If the change is related to a function, put the name of the function early in the bullet.
• If the bullet is related to a GitHub issue or pull request, reference it by number in parentheses before the final period: (#123)..
• Order bullets alphabetically by function name. Put all bullets that don't mention function names at the beginning.