knitr::opts_chunk$set( collapse = TRUE, comment = "#>", fig.path = "man/figures/vignette_intro-", dpi = 92, fig.retina = 2 )
When developing R packages, it's good practice to build a good set of unit and regression tests that will notify you when something breaks in the future. For this, the testthat
package is commonly used.
Often though, we end up writing a similar set of tests again and again, which can be both tedious and time-consuming.
xpectr
helps you by generating common testthat
tests. Its goal is not to replace the active thinking process of finding meaningful tests for your functions, but to help systematize and ease that process.
One such example is gxs_function()
, which generates tests for a set of argument value combinations. This allows you to focus on the selection of argument values to test. Once the tests have been generated, you can go through each of them to ensure your function is working as intended and to add relevant tests.
Note: If you comment out the call to gxs_function()
, it is easy to later regenerate the tests. By using a diff tool, you can check that only the intended changes have been made to the file.
Install the CRAN version with:
install.packages("xpectr")
Install the development version with:
# install.packages("devtools") devtools::install_github("ludvigolsen/xpectr")
These functions are used to generate expectations (gxs).
| Function | Description |
|:---------|:------------|
|gxs_selection()
|Generates testthat::expect_*
statements from a selection (string of code)|
|gxs_function()
|Generates testthat::expect_*
statements for combinations of supplied argument values|
| Function | Description |
|:---------|:------------|
|strip()
|Strips strings of non-alphanumeric characters |
|strip_msg()
|Strips side-effect messages of non-alphanumeric characters and rethrows them |
|suppress_mw()
|Suppresses warnings and messages |
|capture_side_effects()
|Captures errors, warnings, and messages from an expression |
|smpl()
|Samples a vector, factor or data frame with internal random seed |
|simplified_formals()
|Formats formals as easily testable character vector |
|element_lengths()
, element_types()
, element_classes()
|Gets the length/type/class of each element |
|num_total_elements()
|Unlists recursively and finds the total number of elements |
|set_test_seed()
|Set random seed for unit tests compatible with R < 3.6.0
|
| Function | Description |
|:---------|:------------|
|prepare_insertion()
|Collapses a vector of expectation strings and adds indentation |
|capture_parse_eval_side_effects()
|Wraps string in capture_side_effects()
before parsing and evaluating it |
|stop_if()
, warn_if()
, message_if()
|If TRUE
, generate error/warning/message with the supplied message |
| Addin | Description | Suggested Key Command |
|:------|:------------|:-------------------------------------------------------------------|
|Insert Expectations insertExpectationsAddin()
|Generates testthat
expect_*
tests from selected code (with gxs_selection()
) |Alt+E
|
|Initialize test_that()
initializeTestthatAddin()
|Inserts testthat::test_that()
code |Alt+T
|
|Initialize gxs_function()
initializeGXSFunctionAddin()
|Initializes a gxs_function()
call with default values of a function |Alt+F
|
|dput()
selected dputSelectedAddin()
|Applies dput()
to selected code |Alt+D
|
|Wrap string with paste0()
wrapStringAddin()
|Splits selected string every n characters and wraps in paste0()
call |Alt+P
|
|Insert checkmate
AssertCollection
code assertCollectionAddin()
|Inserts code for initializing and reporting a checkmate
AssertCollection
|Alt+C
|
|Navigate To Test File navigateTestFileAddin()
|Navigates to extracted file name and line number. E.g. select or copy test_x.R:5
and it opens /tests/testthat/test_x.R
at line 5
.|Alt+N
|
Suggestion: Add xpectr
in the Suggests
field in the DESCRIPTION
file.
library(xpectr) library(testthat) library(dplyr) # Set a seed # When R > 3.6.0, it sets sampling.kind to "Rounding" to make # tests compatible with previous versions of R set_test_seed(42)
# Some data num_vec <- 1:10 long_vec <- c(LETTERS, letters) a_factor <- factor(c("a","b","c")) df <- data.frame( 'a' = c(1, 2, 3), 'b' = c('t', 'y', 'u'), "c" = a_factor, stringsAsFactors = FALSE ) %>% dplyr::group_by(a) # A function with side effects fn <- function(raise = FALSE){ message("Hi! I'm Kevin, your favorite message!") warning("G'Day Mam! I'm a warning to the world!") message("Kevin is ma name! Yesss!") warning("Hopefully the whole world will see me :o") if (isTRUE(raise)){ stop("Lord Evil Error has arrived! Yeehaaa") } "the output" }
Note: gxs_selection()
can be used with the Insert Expectations
addin. See ?insertExpectationsAddin
for instructions on how to set up a key command.
# Inspect num_vec
num_vec
# Generate expectations gxs_selection("num_vec") # Inserts the following tests: ## Testing 'num_vec' #### ## Initially generated by xpectr xpectr::set_test_seed(42) # Testing class expect_equal( class(num_vec), "integer", fixed = TRUE) # Testing type expect_type( num_vec, type = "integer") # Testing values expect_equal( num_vec, c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10), tolerance = 1e-4) # Testing names expect_equal( names(num_vec), NULL, fixed = TRUE) # Testing length expect_equal( length(num_vec), 10L) # Testing sum of element lengths expect_equal( sum(xpectr::element_lengths(num_vec)), 10L) ## Finished testing 'num_vec' ####
# Inspect a_factor
a_factor
# Generate expectations gxs_selection("a_factor") # Inserts the following tests: ## Testing 'a_factor' #### ## Initially generated by xpectr xpectr::set_test_seed(42) # Testing is factor expect_true( is.factor(a_factor)) # Testing values expect_equal( as.character(a_factor), c("a", "b", "c"), fixed = TRUE) # Testing names expect_equal( names(a_factor), NULL, fixed = TRUE) # Testing length expect_equal( length(a_factor), 3L) # Testing number of levels expect_equal( nlevels(a_factor), 3L) # Testing levels expect_equal( levels(a_factor), c("a", "b", "c"), fixed = TRUE) ## Finished testing 'a_factor' ####
By default, vectors with more than 30 elements will be sampled. This adds smpl()
, which temporarily sets a seed to make sure the same elements are returned every time.
# Inspect long_vec
long_vec
# Generate expectations gxs_selection("long_vec") # Inserts the following tests: ## Testing 'long_vec' #### ## Initially generated by xpectr xpectr::set_test_seed(42) # Testing class expect_equal( class(long_vec), "character", fixed = TRUE) # Testing type expect_type( long_vec, type = "character") # Testing values expect_equal( xpectr::smpl(long_vec, n = 30), c("C", "E", "G", "J", "K", "N", "O", "Q", "R", "S", "T", "W", "Y", "Z", "b", "c", "d", "e", "h", "i", "j", "k", "l", "o", "p", "r", "v", "w", "y", "z"), fixed = TRUE) # Testing names expect_equal( names(xpectr::smpl(long_vec, n = 30)), NULL, fixed = TRUE) # Testing length expect_equal( length(long_vec), 52L) # Testing sum of element lengths expect_equal( sum(xpectr::element_lengths(long_vec)), 52L) ## Finished testing 'long_vec' ####
Data frames are tested columnwise.
# Inspect df
df
# Generate expectations gxs_selection("df") # Inserts the following tests: ## Testing 'df' #### ## Initially generated by xpectr xpectr::set_test_seed(42) # Testing class expect_equal( class(df), c("grouped_df", "tbl_df", "tbl", "data.frame"), fixed = TRUE) # Testing column values expect_equal( df[["a"]], c(1, 2, 3), tolerance = 1e-4) expect_equal( df[["b"]], c("t", "y", "u"), fixed = TRUE) expect_equal( df[["c"]], structure(1:3, levels = c("a", "b", "c"), class = "factor")) # Testing column names expect_equal( names(df), c("a", "b", "c"), fixed = TRUE) # Testing column classes expect_equal( xpectr::element_classes(df), c("numeric", "character", "factor"), fixed = TRUE) # Testing column types expect_equal( xpectr::element_types(df), c("double", "character", "integer"), fixed = TRUE) # Testing dimensions expect_equal( dim(df), c(3L, 3L)) # Testing group keys expect_equal( colnames(dplyr::group_keys(df)), "a", fixed = TRUE) ## Finished testing 'df' ####
When the selected code generates an error, warning or message, we can test those as well. An error is tested with expect_error()
, while messages and warnings are tested as character vectors, to make sure we catch additional warnings/messages.
When running testthat
unit tests on different systems, they sometimes vary in the use of punctuation and newlines (\n). The strip()
and strip_msg()
functions are wrapped around the side effects to remove non-alphanumeric symbols from the tested strings. This helps the expect_*
functions to ignore those differences. In cases where such differences are important to catch, you can set strip = FALSE
in gxs_selection()
.
We assign the output of the function to an output_12345
variable, so we don't have to run it more than once. The number is randomly generated and is not guaranteed to be unique. suppress_mw()
suppresses the messages and warnings.
# Inspect fn
fn
# Generate expectations gxs_selection("fn()") # Inserts the following tests: ## Testing 'fn()' #### ## Initially generated by xpectr xpectr::set_test_seed(42) # Testing side effects # Assigning side effects side_effects_19148 <- xpectr::capture_side_effects(fn(), reset_seed = TRUE) expect_equal( xpectr::strip(side_effects_19148[['warnings']]), xpectr::strip(c("G'Day Mam! I'm a warning to the world!", "Hopefully the whole world will see me :o")), fixed = TRUE) expect_equal( xpectr::strip(side_effects_19148[['messages']]), xpectr::strip(c("Hi! I'm Kevin, your favorite message!\n", "Kevin is ma name! Yesss!\n")), fixed = TRUE) # Assigning output output_19148 <- xpectr::suppress_mw(fn()) # Testing class expect_equal( class(output_19148), "character", fixed = TRUE) # Testing type expect_type( output_19148, type = "character") # Testing values expect_equal( output_19148, "the output", fixed = TRUE) # Testing names expect_equal( names(output_19148), NULL, fixed = TRUE) # Testing length expect_equal( length(output_19148), 1L) # Testing sum of element lengths expect_equal( sum(xpectr::element_lengths(output_19148)), 1L) ## Finished testing 'fn()' #### # In case of errors, the warnings and messages aren't tested gxs_selection("fn(raise = TRUE)") # Inserts the following tests: ## Testing 'fn(raise = TRUE)' #### ## Initially generated by xpectr xpectr::set_test_seed(42) # Testing side effects expect_error( xpectr::strip_msg(fn(raise = TRUE)), xpectr::strip("Lord Evil Error has arrived! Yeehaaa"), fixed = TRUE) ## Finished testing 'fn(raise = TRUE)' ####
When testing the inputs to a function, gxs_function()
allows us to quickly specify values to check and generates tests for each of them.
The first value supplied for an argument is considered the valid baseline value. For each argument, we create tests for each of the supplied values, where the other arguments have their baseline value.
By default, each argument is tested with the NULL
object as well, why we only need to specify it when the baseline value should be NULL
.
It is important that we manually read through the generated tests to make sure that our function is behaving as intended, and to check if any important tests are missing.
# Define a function with arguments fn <- function(x, y, z = 10) { if (x > 3) stop("'x' > 3") if (y < 0) warning("'y'<0") if (z == 10) message("'z' was 10!") x + y + z } # Create tests for the function # Note: We currently need to specify the list of arguments # in the function call gxs_function(fn = fn, args_values = list( "x" = list(2, 4, NA), "y" = list(0,-1), "z" = list(5, 10) )) # Inserts the following tests: ## Testing 'fn' #### ## Initially generated by xpectr # Testing different combinations of argument values # Testing fn(x = 2, y = 0, z = 5) xpectr::set_test_seed(42) # Assigning output output_19148 <- fn(x = 2, y = 0, z = 5) # Testing class expect_equal( class(output_19148), "numeric", fixed = TRUE) # Testing type expect_type( output_19148, type = "double") # Testing values expect_equal( output_19148, 7, tolerance = 1e-4) # Testing names expect_equal( names(output_19148), NULL, fixed = TRUE) # Testing length expect_equal( length(output_19148), 1L) # Testing sum of element lengths expect_equal( sum(xpectr::element_lengths(output_19148)), 1L) # Testing fn(x = 4, y = 0, z = 5) # Changed from baseline: x = 4 xpectr::set_test_seed(42) # Testing side effects expect_error( xpectr::strip_msg(fn(x = 4, y = 0, z = 5)), xpectr::strip("'x' > 3"), fixed = TRUE) # Testing fn(x = NA, y = 0, z = 5) # Changed from baseline: x = NA xpectr::set_test_seed(42) # Testing side effects expect_error( xpectr::strip_msg(fn(x = NA, y = 0, z = 5)), xpectr::strip("missing value where TRUE/FALSE needed"), fixed = TRUE) # Testing fn(x = NULL, y = 0, z = 5) # Changed from baseline: x = NULL xpectr::set_test_seed(42) # Testing side effects expect_error( xpectr::strip_msg(fn(x = NULL, y = 0, z = 5)), xpectr::strip("argument is of length zero"), fixed = TRUE) # Testing fn(x = 2, y = -1, z = 5) # Changed from baseline: y = -1 xpectr::set_test_seed(42) # Testing side effects # Assigning side effects side_effects_16417 <- xpectr::capture_side_effects(fn(x = 2, y = -1, z = 5), reset_seed = TRUE) expect_equal( xpectr::strip(side_effects_16417[['warnings']]), xpectr::strip("'y'<0"), fixed = TRUE) expect_equal( xpectr::strip(side_effects_16417[['messages']]), xpectr::strip(character(0)), fixed = TRUE) # Assigning output output_16417 <- xpectr::suppress_mw(fn(x = 2, y = -1, z = 5)) # Testing class expect_equal( class(output_16417), "numeric", fixed = TRUE) # Testing type expect_type( output_16417, type = "double") # Testing values expect_equal( output_16417, 6, tolerance = 1e-4) # Testing names expect_equal( names(output_16417), NULL, fixed = TRUE) # Testing length expect_equal( length(output_16417), 1L) # Testing sum of element lengths expect_equal( sum(xpectr::element_lengths(output_16417)), 1L) # Testing fn(x = 2, y = NULL, z = 5) # Changed from baseline: y = NULL xpectr::set_test_seed(42) # Testing side effects expect_error( xpectr::strip_msg(fn(x = 2, y = NULL, z = 5)), xpectr::strip("argument is of length zero"), fixed = TRUE) # Testing fn(x = 2, y = 0, z = 10) # Changed from baseline: z = 10 xpectr::set_test_seed(42) # Testing side effects # Assigning side effects side_effects_17365 <- xpectr::capture_side_effects(fn(x = 2, y = 0, z = 10), reset_seed = TRUE) expect_equal( xpectr::strip(side_effects_17365[['warnings']]), xpectr::strip(character(0)), fixed = TRUE) expect_equal( xpectr::strip(side_effects_17365[['messages']]), xpectr::strip("'z' was 10!\n"), fixed = TRUE) # Assigning output output_17365 <- xpectr::suppress_mw(fn(x = 2, y = 0, z = 10)) # Testing class expect_equal( class(output_17365), "numeric", fixed = TRUE) # Testing type expect_type( output_17365, type = "double") # Testing values expect_equal( output_17365, 12, tolerance = 1e-4) # Testing names expect_equal( names(output_17365), NULL, fixed = TRUE) # Testing length expect_equal( length(output_17365), 1L) # Testing sum of element lengths expect_equal( sum(xpectr::element_lengths(output_17365)), 1L) # Testing fn(x = 2, y = 0, z = NULL) # Changed from baseline: z = NULL xpectr::set_test_seed(42) # Testing side effects expect_error( xpectr::strip_msg(fn(x = 2, y = 0, z = NULL)), xpectr::strip("argument is of length zero"), fixed = TRUE) ## Finished testing 'fn' ####
Below, we present the set of RStudio
addins. The intention is for you to set up key commands for the ones you'd like access to. Once you get used to using them, they will speed up your testing process.
Here's a small guide for setting up key comands in RStudio
. We use the Insert Expectations
addin as an example:
After installing the package, go to:
Tools >> Addins >> Browse Addins >> Keyboard Shortcuts
.
Find "Insert Expectations"
and press its field under Shortcut
.
Press desired key command, e.g. Alt+E
.
Press Apply
.
Press Execute
.
The initializeGXSFunctionAddin
initializes the gxs_function()
call with the argument names and default values of a selected function. We can then add the argument values and additional combinations we wish to test. Note, that we don't need to use the default values as our baseline values.
The Tip
comment tells us to comment out the gxs_function()
call after running it, instead of removing it. When you change your code, it's often much quicker to regenerate the tests than to update them manually. You can then use a diff tool to check that only the intended changes were made.
The #
in the end helps the code be inserted right after the call to gxs_function()
.
Suggested keycommand: Alt+F
initializeGXSFunctionAddin("fn") # Inserts the following: # Generate expectations for 'fn' # Tip: comment out the gxs_function() call # so it is easy to regenerate the tests xpectr::set_test_seed(42) xpectr::gxs_function( fn = fn, args_values = list( "x" = list(), "y" = list(), "z" = list(10) ), identation = 2, copy_env = FALSE ) #
The wrapStringAddin
splits long strings and wraps them with paste0()
.
Suggested keycommand: Alt+P
wrapStringAddin("This is a fairly long sentence that we would very very much like to make shorter in our test file!") # Inserts the following: paste0("This is a fairly long sentence that we would very very much ", "like to make shorter in our test file!")
Suggested keycommand: Alt+T
initializeTestthatAddin() # Inserts the following: test_that("testing ...()", { xpectr::set_test_seed(42) # ... })
Suggested keycommand: Alt+C
assertCollectionAddin() # Inserts the following: # Check arguments #### assert_collection <- checkmate::makeAssertCollection() # checkmate::assert_ , add = assert_collection) checkmate::reportAssertions(assert_collection) # End of argument checks ####
Suggested keycommand: Alt+D
v <- c(1, 2, 3) dputSelectedAddin("v") # "v" is the selected code # Inserts the following: c(1, 2, 3)
Suggested keycommand: Alt+N
A common work process in package development is to run Ctrl/Cmd+Shift+L
, which runs all testthat
tests in /tests/testthat/
in the Build
pane.
When a test fails, a message like the following is printed: test_x.R:15: failure: x works
.
If we then copy the test_x.R:15:
part to our clipboard and run navigateTestFileAddin()
, it will open the test_x.R
file and place the cursor at line 15
.
A service like Travis CI
indicate the failed test with (@test_x.R#15)
. The addin therefore also works with test_x.R#15
. If you have additional formats you would like to request, simply open an issue.
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