unitizeR - Interactive R Unit Tests

TL;DR

unitizer simplifies creating, reviewing, and debugging unit tests in R. To install:

install.packages('unitizer')

Please keep in mind this is an experimental framework that has been thoroughly tested by one person.

unitizer bakes in a lot of contextual help so you can get started without reading all the documentation. Try the demo to get an idea:

library(unitizer)
demo(unitizer)

Or check out the screencast to see unitizer in action.

Why Another Testing Framework?

Automated Test Formalization

Are you tired of the deparse/dput then copy-paste R objects into test file dance, or do you use testthat::expect_equal_to_reference a lot?

With unitizer you review function output at an interactive prompt as you would with informal tests. You then store the value, conditions (e.g. warnings, etc.), and environment for use as the reference values in formal tests, all with a single keystroke.

Streamlined Debugging

Do you wish the nature of a test failure was more immediately obvious?

When tests fail, you are shown a proper diff so you can clearly identify how the test failed:

Do you wish that you could start debugging your failed tests without additional set-up work?

unitizer drops you in the test environment so you can debug why the test failed without further ado:

Fast Test Updates

Do you avoid improvements to your functions because that would require painstakingly updating many tests?

The diffs for the failed tests let you immediately confirm only what you intended changed. Then you can update each test with a single keystroke.

Usage

unitizer stores R expressions and the result of evaluating them so that it can detect code regressions. This is akin to saving test output to a .Rout.save file as documented in Writing R Extensions, except that we’re storing the actual R objects and it is much easier to review them.

To use unitizer:

Write test expressions as you would when informally testing code on the command line, and save them to a file (e.g. “my_file_name.R”)
Run unitize("my_file_name.R") and follow the prompts
Continue developing your package
Re-run unitize("my_file_name.R"); if any tests fail you will be able to review and debug them in an interactive prompt

unitizer can run in a non-interactive mode for use with R CMD check.

Documentation

help(package="unitizer"), in particular ?unitize
demo(package="unitizer")
browseVignettes("unitizer") for a list of vignettes, or skip straight to the Introduction vignette

Acknowledgments

Thank you to:

R Core for developing and maintaining such a wonderfully language.
CRAN maintainers, for patiently shepherding packages onto CRAN and maintaining the repository, and Uwe Ligges in particular for maintaining Winbuilder.
Hadley Wickham for testthat from which we borrow many concepts and use for internal tests, for devtools, and for his many other packages.
Gábor Csárdi for crayon through which we can add a new dimension to the R experience.
Jim Hester because covr rocks.
Dirk Eddelbuettel and Carl Boettiger for the rocker project, and Gábor Csárdi and the R-consortium for Rhub, without which testing bugs on R-devel and other platforms would be a nightmare.
Yihui Xie for knitr and J.J. Allaire et al. for rmarkdown, and by extension John MacFarlane for pandoc.
@kohler for gifsicle and the ffmpeg team for ffmpeg.
All open source developers out there that make their work freely available for others to use.
Github, Travis-CI, Codecov, Vagrant, Docker, Ubuntu, Brew for providing infrastructure that greatly simplifies open source development.
Free Software Foundation for developing the GPL license and promotion of the free software movement.

About the Author

Brodie Gaslam is a hobbyist programmer based in the US East Coast.