Where should I put data for automated tests with testthat?

Question

I am using Hadley's testthat-based approach for automated testing of my package.

With this approach, what is the most suitable place to put test data files that is files only used by the test scripts in tests/testthat), but not by any other functions in R/?

My current approach is to put them in tests/testdata, and then read.table from there with a relative path rather than with system.file (in order to avoid the need to install the package to run tests).

Is there a standard way to do this?

Answer 1

Lifting from Ben Bolker's comments:

I use inst/testdata and then system.file("testdata",...,package="my_package")

The advantage of this method:

• You can keep your file structure neat, especially if you have many data files and/or tests.
• The fact that files in inst are installed is long-standing canonical R practice; it seems safer that system.file("testdata", "some_file") will always work than that ../testdata/some_file will do. I've had bad experiences using relative file paths when doing R CMD check.
• Unlike Sathish's answer, it doesn't depend on your data being "stored" as R code.

Answer 2

• tests are kept inside a file which is prefixed with 'test_'
• data are kept inside files prefixed with 'helper_'

Package Directory and File Structure:

└──pkg_name/
    ├── DESCRIPTION
    ├── NAMESPACE
    ├──.Rbuildignore
    ├── data/
    ├── man/
    ├── R/
    ├── vignettes/
    └── tests/
        ├── testthat.R
        └── testthat/
             └── helper_myfunc1.R
             └── helper_myfunc2.R
             └── test_pkg_name.R

testthat.R

library(testthat)
library(pkg_name)
test_check("pkg_name")

helper_myfunc1.R contains data for testing myfunc1 function

a1 <- 2
a2 <- 2
b1 <- 2*3
b2 <- 6

helper_myfunc2.R contains data for testing myfunc2 function

c1 <- 50/2
c2 <- 25
d1 <- c(2,3)
d2 <- c(2,3)

test_pkg_name.R contains tests for functions and other objects in the package

context('pkg_name_functions')

test_that('myfunc1',
          {
            expect_identical(a1, a2)
            expect_identical(b1, b2)
          })

test_that('myfunc2',
          {
            expect_identical(c1, c2)
            expect_identical(d1, d2)
          })

Conduct unit testing

library("devtools")

devtools::load_all()
# Loading pkg_name

devtools::test()
# Loading pkg_name
# Testing pkg_name
# pkg_name_functions: ....

# DONE ================================================================

Answer 3

The Data chapter of the same R-Pkgs book says "it’s ok to put small files directly in your test directory". That's what I've done in the past. And it sounds like that's what you're already doing, plus the testdata directory.