# R Package Development

R package development with devtools, testthat, and roxygen2.

- Repository: https://github.com/posit-dev/skills (551 stars)
- Category: Testing
- License: MIT
- Last updated: 2026-10-28
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add posit-dev/skills --skill r-package-development -g -a claude-code -y`
Codex: `npx skills add posit-dev/skills --skill r-package-development -g -a codex -y`
Cursor: `npx skills add posit-dev/skills --skill r-package-development -g -a cursor -y`
Gemini CLI: `npx skills add posit-dev/skills --skill r-package-development -g -a gemini-cli -y`
Claude Code plugin marketplace: `/plugin marketplace add posit-dev/skills`

## 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.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# R package development

## 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.

The rest: https://github.com/posit-dev/skills/blob/HEAD/r-lib/r-package-development/SKILL.md