Where to place library calls with testthat?

Question

I am looking for best practice help with the brilliant testthat. Where is the best place to put your library(xyzpackage) calls to use all the package functionality?

I first have been setting up a runtest.R setting up paths and packages. I then run test_files(test-code.R) which only holds context and tests. Example for structure follows:

# runtests.R
library(testthat)
library(data.table)

source("code/plotdata-fun.R")

mytestreport <- test_file("code/test-plotdata.R")

# does other stuff like append date and log test report (not shown)

and in my test files e.g. test-plotdata.R (a stripped down version):

#my tests for plotdata
context("Plot Chart")

test_that("Inputs valid", {

  test.dt  = data.table(px = c(1,2,3), py = c(1,4,9))
  test.notdt <- c(1,2,3)

  # illustrating the check for data table as first param in my code
  expect_error(PlotMyStandardChart(test.notdt, 
                                   plot.me = FALSE),
                "Argument must be data table/frame")

  # then do other tests with test.dt etc...
})

1. Is this the way @hadley intended it to be used? It is not clear from the journal article. Should I also be duplicating library calls in my test files as well? Do you need a library set up in each context, or just one at start of file?

2. Is it okay to over-call library(package) in r?

3. To use the test_dir() and other functionality what is best way to set up your files. I do use require() in my functions, but I also set up test data examples in the contexts. (In above example, you will see I would need data.table package for test.dt to use in other tests).

Thanks for your help.

Felipe

All your questions are a matter of coding conventions, really. There is not much difference between these options. Calling library multiple times is not a problem. I usually place all such calls in the main file and do not duplicate them, but you're free to do anything you want: your package -- your rules. – Crosshatch

Are you just providing tests for some scripts or is this for a package of your own? If the latter, the proper use is documented on Hadley's Testing R packages page. It is extremely easy to use with Rstudio. – Adherent

Thanks @cdeterman. No this is just for scripts. I am still too much of a R beginner to try to build a package as yet. – Felipe

Answer 1

Some suggestions / comments:

• set up each file so that it can be run on its own with test_file without additional setup. This way you can easily run an individual file while developing if you are just focusing on one small part of a larger project (useful if running all your tests is slow)
• there is little penalty to calling library multiple times as that function first checks to see if the package is already attached
• if you set up each file so that it can be run with test_file, then test_dir will work fine without having to do anything additional
• you don't need to library(testthat) in any of your test files since presumably you are running them with test_file or test_dir, which would require testthat to be loaded

Also, you can just look at one of Hadley's recent packages to see how he does it (e.g. dplyr tests).

Malcom

Thanks BrodieG, that pointer to look at Hadley's dplyr tests was a great idea! +1 for others trying to learn testthat – Felipe

Answer 2

If you use devtools::test(filter="mytestfile") then devtools will take care of calling helper files etc. for you. In this way you don't need to do anything special to make your test file work on its own. Basically, this is just the same as if you ran a test, but only had test_mytestfile.R in your testthat folder.

Rotman