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My Organization's First R package

Test R Code

rstudio::conf(2020L)

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It’s not that you don’t test your code, it’s that you don’t automate your tests.

—Hadley Wickham

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testthat: Unit tests for R



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testthat: Unit tests for R

Automate tests (use_test()) using expectations

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testthat: Unit tests for R

Automate tests (use_test()) using expectations

Run tests with test(), test_file(), Cmd/Ctrl + Shift + T.

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testthat: Unit tests for R

Automate tests (use_test()) using expectations

Run tests with test(), test_file(), Cmd/Ctrl + Shift + T.

Also runs during R CMD Check (check())

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Test files

test/testthat/test-themes.R

test_that("theme works", {
  expect_true(ggplot2::is.theme(theme_mako()))
  expect_error(theme_mako(base_size = "14"))
})
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Test files

test/testthat/test-themes.R

test_that("theme works", {
  expect_true(ggplot2::is.theme(theme_mako()))
  expect_error(theme_mako(base_size = "14"))
})
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Test files

test/testthat/test-themes.R

test_that("theme works", {
  expect_true(ggplot2::is.theme(theme_mako()))
  expect_error(theme_mako(base_size = "14"))
})
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Test files

test/testthat/test-themes.R

test_that("theme works", {
  expect_true(ggplot2::is.theme(theme_mako())) 
  expect_error(theme_mako(base_size = "14"))
})
test()
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Test files

test/testthat/test-themes.R

test_that("theme works", {
  expect_true(ggplot2::is.theme(theme_mako())) 
  expect_error(theme_mako(base_size = "14"))
})
test()
## Loading shinRa
## Testing shinRa
## ✓ |  OK F W S | Context
## ✓ |   2       | themes
## 
## ══ Results ════════════════════════
## OK:       2
## Failed:   0
## Warnings: 0
## Skipped:  0
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Test files

test/testthat/test-themes.R

test_that("theme works", {
  expect_true(ggplot2::is.theme(theme_mako()))
  expect_error(theme_mako(base_size = "14"))
  expect_equal(theme_mako(), ggplot2::theme_dark())
})
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test()
Loading shinRa
✓ |  OK F W S | Context
x |   2 1     | themes
────────────────────────────────────
test-themes.R:4: failure: theme works
theme_mako() not equal to ggplot2::theme_dark().
Component “line”: Component “size”: Mean relative difference: 0.2142857
Component “rect”: Component “size”: Mean relative difference: 0.2142857
Component “text”: Component “size”: Mean relative difference: 0.2142857
Component “axis.title.x”: Component “margin”: Mean relative difference: 0.2142857
Component “axis.title.x.top”: Component “margin”: Mean relative difference: 0.2142857
Component “axis.title.y”: Component “margin”: Mean relative difference: 0.2142857
Component “axis.title.y.right”: Component “margin”: Mean relative difference: 0.2142857
Component “axis.text.x”: Component “margin”: Mean relative difference: 0.2142857
Component “axis.text.x.top”: Component “margin”: Mean relative difference: 0.21
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Test files

test/testthat/test-themes.R

test_that("theme works", {
  expect_true(ggplot2::is.theme(theme_mako()))
  expect_error(theme_mako(base_size = "14"))
  expect_equal(theme_mako(), ggplot2::theme_dark())
})
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Expectations (expect_*())

function expectation
expect_equal(x, y) the same, more or less
expect_identical(x, y) the exact same
expect_message/warning/error(x, y) a message, warning, or error
expect_true(x) TRUE
expect_is(x, y) x is class y
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Expectations (expect_*())

function expectation
expect_equal(x, y) the same, more or less
expect_identical(x, y) the exact same
expect_message/warning/error(x, y) a message, warning, or error
expect_true(x) TRUE
expect_is(x, y) x is class y

MANY more. See https://r-pkgs.org/tests.html

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Your Turn 1

Use use_test() to create a new file. Call it "resident_connection"

Change the test description (the first argument of test_that()) to "connection is returning valid data"

In the test_that() function, remove the default expectations. Replace them with this code

Re-load your package.

Press the "Run tests" button in RStudio (above the script pane) or run test_file("tests/testthat/test-resident_connection.R") in the console.

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Your Turn 1

use_test("resident_connection")

In test-resident_connection.R

test_that("connection is returning valid data", {
  # `resident_data` is a tibble, isn't empty, and has the right columns
  resident_data <- get_resident_data()
  expect_is(resident_data, c("tbl_df", "tbl", "data.frame"))
  expect_gt(nrow(resident_data), 0)
  expect_named(resident_data, c("sector", "residents"))
  # `resident_data_dt` is a data.table
  resident_data_dt <- get_resident_data(data_table = TRUE)
  expect_is(resident_data_dt, c("data.table", "data.frame"))
})
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Your Turn 2

Run all the tests in the package using test(). Fix the broken tests.

Hint: The bug is in R/summarize_data.R

Re-run the tests until all of them pass

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Your Turn 2

segment_reactor_output <- function(reactor_num, data_table = FALSE) {
  reactor_output <- hack_shinra_data(data_table = data_table)
  dplyr::filter(reactor_output, .data$reactor == reactor_num)
}
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use_r() 🤝 use_test()

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Organizing tests (VERY soft guidelines)

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Organizing tests (VERY soft guidelines)

One test file for each R file

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Organizing tests (VERY soft guidelines)

One test file for each R file

One test for every behavior tested

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Organizing tests (VERY soft guidelines)

One test file for each R file

One test for every behavior tested

One expectation for every aspect of the test

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What should I test? (VERY soft guidelines)

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What should I test? (VERY soft guidelines)

External behavior.

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What should I test? (VERY soft guidelines)

External behavior.

Don't bother with simple code (unless it's not that simple after all 😬)

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Find a bug, write a test

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Skipping tests (skip_*())

function
skip()
skip_if()
skip_on_cran()
skip_on_travis()
skip_on_os()
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Skipping tests (skip_*())

function
skip()
skip_if()
skip_on_cran()
skip_on_travis()
skip_on_os()

MANY more. See ?testthat::skip

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R CMD Check

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R CMD Check

The gold standard

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R CMD Check

The gold standard

Builds pkg and docs, checks code quality, runs examples, runs tests, and more!

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R CMD Check

The gold standard

Builds pkg and docs, checks code quality, runs examples, runs tests, and more!

check() or Cmd/Ctrl + Shift + E

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R CMD Check

The gold standard

Builds pkg and docs, checks code quality, runs examples, runs tests, and more!

check() or Cmd/Ctrl + Shift + E

See all the details at https://r-pkgs.org/r-cmd-check.html

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check early, check often

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Your Turn 3

Run check() or Cmd/Ctrl + Shift + E

Fix the warnings. Re-run check() until you get a clean bill of health.

Hint: segment_reactor_output() is in R/summarize_data.R

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Your Turn 3

use_package("dplyr")
#' Segment Shinra reactor data
#'
#' @param reactor_num The reactor number to segment by.
#' @inheritParams hack_shinra_data
#'
#' @return a tibble or data.table filtered by `reactor_num`
#' @export
#'
#' @examples
#'
#' segment_reactor_output(7)
#'
segment_reactor_output <- function(reactor_num, data_table = FALSE) {
  reactor_output <- hack_shinra_data(data_table = data_table)
  dplyr::filter(reactor_output, .data$reactor == reactor_num)
}
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R CMD Check Results

result meaning fix required for CRAN?
Error A severe problem. Always fix. Yes
Warning A probable problem. Almost always fix. Yes
Note A potential issue. Strive to fix. More or less
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R CMD Check Results

result meaning fix required for CRAN?
Error A severe problem. Always fix. Yes
Warning A probable problem. Almost always fix. Yes
Note A potential issue. Strive to fix. More or less

Shoot for all 0s under almost all circumstances!

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Types of test files

type file run
test test-*.R alphabetical order
helper helper-*.R before tests, from load_all()
setup setup-*.R before tests, not from load_all()
teardown teardown-*.R after tests
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Types of test files

type file run
test test-*.R alphabetical order
helper helper-*.R before tests, from load_all()
setup setup-*.R before tests, not from load_all()
teardown teardown-*.R after tests

All located in tests/testthat/

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Your Turn 4

Both test-count-donations.R and test-tables.R use donations_test_data. Let's move it to a helper file. First, create the file with fs::file_create("tests/testthat/helper-donations_data.R"). Open it manually or use edit_file().

Move the code to create donations_test_data into helper-donations_data.R.

Remove the donations_test_data code from the two test files.

Run the tests.

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Your Turn 4

fs::file_create("tests/testthat/helper-donations_data.R")

In tests/testthat/helper-donations_data.R

donations_test_data <- data.frame(
  donor_id = 1:15,
  sector = c(7L, 2L, 8L, 6L, 5L, 5L, 8L, 1L, 5L, 4L, 4L, 3L, 7L, 5L, 8L),
  donation = c(
    529.58, 16.64, 410.88, 448.73, 211.62, 642.53, 410.93,
    707.38, 30.19, 573.02, 286.31, 734.73, 971.81, 30, 465.92
  )
)
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Test Coverage

Lines of code tested (via the covr R pkg)

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Test Coverage

Lines of code tested (via the covr R pkg)

use_coverage() (via codecov, coveralls)

test_coverage()

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Continuous Integration (CI)

Run R CMD Check with every commit

Travis, Appveyor, others

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Continuous Integration (CI)

Run R CMD Check with every commit

Travis, Appveyor, others

use_travis(), use_appveyor(), etc

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GitHub Actions

All of the above and more!

Newer service

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GitHub Actions

All of the above and more!

Newer service

use_github_actions_*()

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Resources

Advanced R, ch. 22: "Debugging"

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