R Package Development Workflow

Typical workflow

When developing a new function

1. write a test (optional / only when trying to do test-driven development)
2. run the tests to see it fail

devtools::test()

or CTRL+SHIFT+T (Win+Linux) or CMD+SHIFT+T (Mac)

3. write (a draft of) a function in R/, document it with roxygen comments (R6 specifics here or by looking at R6 based packages)
4. Load the function and "test" in the R terminal

devtools::load_all()

or CTRL+SHIFT+L (Win+Linux) or CMD+SHIFT+L (Mac)

5. IF you already know how to do this, write unit test(s) for your function (see here) - if you don't know this yet, ask the others :)
6. Run all tests to see whether everything is still working (see 2.)

Repeat 1-6

7. Check your style and update your code accordingly

styler::style_pkg(style = styler::tidyverse_style, indent_by = 4) 

every once in a while / before committing

8. check the package: this will not only run unit tests but will also check other aspects of the package, like whether documentation is complete, the DESCRIPTION file is ok, ...

devtools::check()

or

rcmdcheck::rcmdcheck()

9. Update documentation: If you add or export new functions / classes or add / remove arguments, you should update the documentation

devtools::document()

or CTRL+SHIFT+D (Win+Linux) or CMD+SHIFT+D (Mac)

Shortcuts overview

Description	Win + Linux	Mac
Load All (devtools)	CTRL+SHIFT+L	CMD+SHIFT+L
Test Package (Desktop)	CTRL+SHIFT+T	CMD+SHIFT+T
Document Package	CMD+SHIFT+D	CMD+SHIFT+D
Check Package	CMD+SHIFT+E	CMD+SHIFT+E
(Build and Reload)	CMD+SHIFT+B	CMD+SHIFT+B

• Full list of RStudio Keyboard Shortcuts

Note on VSCode: If you develop in VSCode, you can add shortcuts by opening your keybindings.json ("Open Keyboard Shortcuts (JSON)") and adding blocks like this:

{
    "description": "run all tests",
    "key": "cmd+shift+t",
    "command": "r.runCommand",
    "when": "editorLangId == r && editorTextFocus || terminalFocus",
    "args": "devtools::test()"
}

Misc

folders

• R code goes into R
• tests go into tests/testthat
• man contains the documentation for the package (see below)
• if we want to have internal or external data, this blog post is a great resource

dependencies

• the NAMESPACE chapter is quite informative to read
• add it to the "Imports" in the DESCRIPTION file -> this ensures that the package is installed when the user installs the package
• in your function, use the :: notation to refer to the function, e.g. crul::HttpClient
• according to R packages this is the preferred way
  • unless we use a function a lot, then we could also use the @importFrom roxygen tag, cf. here