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This package provides two simple functions (30 lines of code in total):


The reason is laziness. It is tedious to type these commands repeatedly in tests:

message('checking if these numbers are equal...')
stopifnot(all.equal(1, 1+1e-10), 10*.1 == 1)

message('checking if a non-exported function works...')
stopifnot(is.character(package:::utility_foo(x = 'abcd', y = 1:100)))

With the two simple functions above, we type six letters (assert) instead of sixteen (message + stopifnot), and assert is also a more intuitive function name for testing purposes (you assert a fact followed by evidence):

  'these numbers are equal',
  all.equal(1, 1+1e-10), 10*.1 == 1

  'a non-exported function works',
  is.character(utility_foo(x = 'abcd', y = 1:100))

assert('T is TRUE and F is FALSE by default', {
  (T == TRUE)
  (F == FALSE)

R CMD check

Put the tests under the directory pkg_name/tests/testit/ (where pkg_name is the root directory of your package), and write a test-all.R under pkg_name/tests/:


That is all for R CMD check. For package development, it is recommended to use devtools. In particular, Ctrl + Shift + L in RStudio makes all objects in a package visible to you, and you can play with the tests freely.


Stable version on CRAN:


Development version:



How about testthat? Well, this package is far less sophisticated than testthat. There is nothing fancy in this package. Please do consider testthat if your tests require more granularity. I myself do not use testthat because I find it unnecessary to invent a new vocabulary (testthat::expect_xxx), and the error message of testthat is somehow obscure in my eyes. For testit, I do not need to think if I should use expect_equal, expect_equivalent, or expect_identical; I just write test conditions that return TRUE or FALSE. That is the only single rule to remember.

There is no plan to add new features or reinvent anything in this package. It is an intentionally tiny package.


Although he did not really mean it, Xunzi said something that happens to apply well to unit testing:


This package is free and open source software, licensed under GPL.