testthat 
Overview
Testing your code can be painful and tedious, but it greatly increases the quality of your code. testthat tries to make testing as fun as possible, so that you get a visceral satisfaction from writing tests. Testing should be addictive, so you do it all the time. To make that happen, testthat:
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Provides functions that make it easy to describe what you expect a function to do, including catching errors, warnings, and messages.
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Easily integrates in your existing workflow, whether itโs informal testing on the command line, building test suites, or using R CMD check.
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Displays test progress visually, showing a pass, fail, or error for every expectation. If youโre using the terminal or a recent version of RStudio, itโll even colour the output.
testthat draws inspiration from the xUnit family of testing packages, as well as from many of the innovative ruby testing libraries, like rspec, testy, bacon and cucumber.
testthat is the most popular unit testing package for R and is used by thousands of CRAN packages.
If youโre not familiar with testthat, the testing chapter in R packages gives a good overview, along with workflow advice and concrete examples.
Installation
# Install the released version from CRAN
install.packages("testthat")
# Or the development version from GitHub:
# install.packages("pak")
pak::pak("r-lib/testthat")Usage
The easiest way to get started is with
usethis. Assuming youโre in a
package directory, just run usethis::use_test("name") to create a test
file, and set up all the other infrastructure you need. If youโre using
RStudio, press Cmd/Ctrl + Shift + T (or run devtools::test() if not)
to run all the tests in a package.