Package 'testthat'

Description

The idea behind auto_test() is that you just leave it running while you develop your code. Every time you save a file it will be automatically tested and you can easily see if your changes have caused any test failures.

Usage

auto_test(
  code_path,
  test_path,
  reporter = default_reporter(),
  env = test_env(),
  hash = TRUE
)

Arguments

Details

The current strategy for rerunning tests is as follows:

• if any code has changed, then those files are reloaded and all tests rerun

• otherwise, each new or modified test is run

In the future, auto_test() might implement one of the following more intelligent alternatives:

• Use codetools to build up dependency tree and then rerun tests only when a dependency changes.

• Mimic ruby's autotest and rerun only failing tests until they pass, and then rerun all tests.

See Also

auto_test_package()

Description

Watches a package for changes, rerunning tests as appropriate.

Usage

auto_test_package(pkg = ".", reporter = default_reporter(), hash = TRUE)

Arguments

See Also

auto_test() for details on how method works

Description

⁠R CMD check⁠ displays only the last 13 lines of the result, so this report is designed to ensure that you see something useful there.

See Also

Other reporters: DebugReporter, FailReporter, JunitReporter, ListReporter, LocationReporter, MinimalReporter, MultiReporter, ProgressReporter, RStudioReporter, Reporter, SilentReporter, StopReporter, SummaryReporter, TapReporter, TeamcityReporter

Description

Does code return a number greater/less than the expected value?

Usage

expect_lt(object, expected, label = NULL, expected.label = NULL)

expect_lte(object, expected, label = NULL, expected.label = NULL)

expect_gt(object, expected, label = NULL, expected.label = NULL)

expect_gte(object, expected, label = NULL, expected.label = NULL)

Arguments

See Also

Other expectations: equality-expectations, expect_error(), expect_length(), expect_match(), expect_named(), expect_null(), expect_output(), expect_reference(), expect_silent(), inheritance-expectations, logical-expectations

Examples

a <- 9
expect_lt(a, 10)

## Not run: 
expect_lt(11, 10)

## End(Not run)

a <- 11
expect_gt(a, 10)
## Not run: 
expect_gt(9, 10)

## End(Not run)

Description

This reporter will call a modified version of recover() on all broken expectations.

See Also

Other reporters: CheckReporter, FailReporter, JunitReporter, ListReporter, LocationReporter, MinimalReporter, MultiReporter, ProgressReporter, RStudioReporter, Reporter, SilentReporter, StopReporter, SummaryReporter, TapReporter, TeamcityReporter

Description

A simple behavior-driven development (BDD) domain-specific language for writing tests. The language is similar to RSpec for Ruby or Mocha for JavaScript. BDD tests read like sentences and it should thus be easier to understand what the specification of a function/component is.

Usage

describe(description, code)

it(description, code = NULL)

Arguments

Details

Tests using the describe syntax not only verify the tested code, but also document its intended behaviour. Each describe block specifies a larger component or function and contains a set of specifications. A specification is defined by an it block. Each it block functions as a test and is evaluated in its own environment. You can also have nested describe blocks.

This test syntax helps to test the intended behaviour of your code. For example: you want to write a new function for your package. Try to describe the specification first using describe, before your write any code. After that, you start to implement the tests for each specification (i.e. the it block).

Use describe to verify that you implement the right things and use test_that() to ensure you do the things right.

Examples

describe("matrix()", {
  it("can be multiplied by a scalar", {
    m1 <- matrix(1:4, 2, 2)
    m2 <- m1 * 2
    expect_equal(matrix(1:4 * 2, 2, 2), m2)
  })
  it("can have not yet tested specs")
})

# Nested specs:
## code
addition <- function(a, b) a + b
division <- function(a, b) a / b

## specs
describe("math library", {
  describe("addition()", {
    it("can add two numbers", {
      expect_equal(1 + 1, addition(1, 1))
    })
  })
  describe("division()", {
    it("can divide two numbers", {
      expect_equal(10 / 2, division(10, 2))
    })
    it("can handle division by 0") #not yet implemented
  })
})

Description

These functions provide two levels of strictness when comparing a computation to a reference value. expect_identical() is the baseline; expect_equal() relaxes the test to ignore small numeric differences.

In the 2nd edition, expect_identical() uses identical() and expect_equal uses all.equal(). In the 3rd edition, both functions use waldo. They differ only in that expect_equal() sets tolerance = testthat_tolerance() so that small floating point differences are ignored; this also implies that (e.g.) 1 and 1L are treated as equal.

Usage

expect_equal(
  object,
  expected,
  ...,
  tolerance = if (edition_get() >= 3) testthat_tolerance(),
  info = NULL,
  label = NULL,
  expected.label = NULL
)

expect_identical(
  object,
  expected,
  info = NULL,
  label = NULL,
  expected.label = NULL,
  ...
)

Arguments

See Also

• expect_setequal()/expect_mapequal() to test for set equality.

• expect_reference() to test if two names point to same memory address.

Other expectations: comparison-expectations, expect_error(), expect_length(), expect_match(), expect_named(), expect_null(), expect_output(), expect_reference(), expect_silent(), inheritance-expectations, logical-expectations

Examples

a <- 10
expect_equal(a, 10)

# Use expect_equal() when testing for numeric equality
## Not run: 
expect_identical(sqrt(2) ^ 2, 2)

## End(Not run)
expect_equal(sqrt(2) ^ 2, 2)

Description

Call expect() when writing your own expectations. See vignette("custom-expectation") for details.

Usage

expect(
  ok,
  failure_message,
  info = NULL,
  srcref = NULL,
  trace = NULL,
  trace_env = caller_env()
)

Arguments

Details

While expect() creates and signals an expectation in one go, exp_signal() separately signals an expectation that you have manually created with new_expectation(). Expectations are signalled with the following protocol:

• If the expectation is a failure or an error, it is signalled with base::stop(). Otherwise, it is signalled with base::signalCondition().

• The continue_test restart is registered. When invoked, failing expectations are ignored and normal control flow is resumed to run the other tests.

Value

An expectation object. Signals the expectation condition with a continue_test restart.

See Also

exp_signal()

Description

expect_error(), expect_warning(), expect_message(), and expect_condition() check that code throws an error, warning, message, or condition with a message that matches regexp, or a class that inherits from class. See below for more details.

In the 3rd edition, these functions match (at most) a single condition. All additional and non-matching (if regexp or class are used) conditions will bubble up outside the expectation. If these additional conditions are important you'll need to catch them with additional expect_message()/expect_warning() calls; if they're unimportant you can ignore with suppressMessages()/suppressWarnings().

It can be tricky to test for a combination of different conditions, such as a message followed by an error. expect_snapshot() is often an easier alternative for these more complex cases.

Usage

expect_error(
  object,
  regexp = NULL,
  class = NULL,
  ...,
  inherit = TRUE,
  info = NULL,
  label = NULL
)

expect_warning(
  object,
  regexp = NULL,
  class = NULL,
  ...,
  inherit = TRUE,
  all = FALSE,
  info = NULL,
  label = NULL
)

expect_message(
  object,
  regexp = NULL,
  class = NULL,
  ...,
  inherit = TRUE,
  all = FALSE,
  info = NULL,
  label = NULL
)

expect_condition(
  object,
  regexp = NULL,
  class = NULL,
  ...,
  inherit = TRUE,
  info = NULL,
  label = NULL
)

Arguments

Value

If regexp = NA, the value of the first argument; otherwise the captured condition.

Testing message vs class

When checking that code generates an error, it's important to check that the error is the one you expect. There are two ways to do this. The first way is the simplest: you just provide a regexp that match some fragment of the error message. This is easy, but fragile, because the test will fail if the error message changes (even if its the same error).

A more robust way is to test for the class of the error, if it has one. You can learn more about custom conditions at https://adv-r.hadley.nz/conditions.html#custom-conditions, but in short, errors are S3 classes and you can generate a custom class and check for it using class instead of regexp.

If you are using expect_error() to check that an error message is formatted in such a way that it makes sense to a human, we recommend using expect_snapshot() instead.

See Also

expect_no_error(), expect_no_warning(), expect_no_message(), and expect_no_condition() to assert that code runs without errors/warnings/messages/conditions.

Other expectations: comparison-expectations, equality-expectations, expect_length(), expect_match(), expect_named(), expect_null(), expect_output(), expect_reference(), expect_silent(), inheritance-expectations, logical-expectations

Examples

# Errors ------------------------------------------------------------------
f <- function() stop("My error!")
expect_error(f())
expect_error(f(), "My error!")

# You can use the arguments of grepl to control the matching
expect_error(f(), "my error!", ignore.case = TRUE)

# Note that `expect_error()` returns the error object so you can test
# its components if needed
err <- expect_error(rlang::abort("a", n = 10))
expect_equal(err$n, 10)

# Warnings ------------------------------------------------------------------
f <- function(x) {
  if (x < 0) {
    warning("*x* is already negative")
    return(x)
  }
  -x
}
expect_warning(f(-1))
expect_warning(f(-1), "already negative")
expect_warning(f(1), NA)

# To test message and output, store results to a variable
expect_warning(out <- f(-1), "already negative")
expect_equal(out, -1)

# Messages ------------------------------------------------------------------
f <- function(x) {
  if (x < 0) {
    message("*x* is already negative")
    return(x)
  }

  -x
}
expect_message(f(-1))
expect_message(f(-1), "already negative")
expect_message(f(1), NA)

Description

Use this to test whether a function returns a visible or invisible output. Typically you'll use this to check that functions called primarily for their side-effects return their data argument invisibly.

Usage

expect_invisible(call, label = NULL)

expect_visible(call, label = NULL)

Arguments

Value

The evaluated call, invisibly.

Examples

expect_invisible(x <- 10)
expect_visible(x)

# Typically you'll assign the result of the expectation so you can
# also check that the value is as you expect.
greet <- function(name) {
  message("Hi ", name)
  invisible(name)
}
out <- expect_invisible(greet("Hadley"))
expect_equal(out, "Hadley")

Description

Does code return a vector with the specified length?

Usage

expect_length(object, n)

Arguments

See Also

expect_vector() to make assertions about the "size" of a vector

Other expectations: comparison-expectations, equality-expectations, expect_error(), expect_match(), expect_named(), expect_null(), expect_output(), expect_reference(), expect_silent(), inheritance-expectations, logical-expectations

Examples

expect_length(1, 1)
expect_length(1:10, 10)

## Not run: 
expect_length(1:10, 1)

## End(Not run)

Description

You can either check for the presence of names (leaving expected blank), specific names (by supplying a vector of names), or absence of names (with NULL).

Usage

expect_named(
  object,
  expected,
  ignore.order = FALSE,
  ignore.case = FALSE,
  info = NULL,
  label = NULL
)

Arguments

See Also

Other expectations: comparison-expectations, equality-expectations, expect_error(), expect_length(), expect_match(), expect_null(), expect_output(), expect_reference(), expect_silent(), inheritance-expectations, logical-expectations

Examples

x <- c(a = 1, b = 2, c = 3)
expect_named(x)
expect_named(x, c("a", "b", "c"))

# Use options to control sensitivity
expect_named(x, c("B", "C", "A"), ignore.order = TRUE, ignore.case = TRUE)

# Can also check for the absence of names with NULL
z <- 1:4
expect_named(z, NULL)

Description

These expectations are the opposite of expect_error(), expect_warning(), expect_message(), and expect_condition(). They assert the absence of an error, warning, or message, respectively.

Usage

expect_no_error(object, ..., message = NULL, class = NULL)

expect_no_warning(object, ..., message = NULL, class = NULL)

expect_no_message(object, ..., message = NULL, class = NULL)

expect_no_condition(object, ..., message = NULL, class = NULL)

Arguments

Examples

expect_no_warning(1 + 1)

foo <- function(x) {
  warning("This is a problem!")
}

# warning doesn't match so bubbles up:
expect_no_warning(foo(), message = "bananas")

# warning does match so causes a failure:
try(expect_no_warning(foo(), message = "problem"))

Description

Test for output produced by print() or cat(). This is best used for very simple output; for more complex cases use expect_snapshot().

Usage

expect_output(
  object,
  regexp = NULL,
  ...,
  info = NULL,
  label = NULL,
  width = 80
)

Arguments

Value

The first argument, invisibly.

See Also

Other expectations: comparison-expectations, equality-expectations, expect_error(), expect_length(), expect_match(), expect_named(), expect_null(), expect_reference(), expect_silent(), inheritance-expectations, logical-expectations

Examples

str(mtcars)
expect_output(str(mtcars), "32 obs")
expect_output(str(mtcars), "11 variables")

# You can use the arguments of grepl to control the matching
expect_output(str(mtcars), "11 VARIABLES", ignore.case = TRUE)
expect_output(str(mtcars), "$ mpg", fixed = TRUE)

Description

• expect_setequal(x, y) tests that every element of x occurs in y, and that every element of y occurs in x.

• expect_contains(x, y) tests that x contains every element of y (i.e. y is a subset of x).

• expect_in(x, y) tests every element of x is in y (i.e. x is a subset of y).

• expect_mapequal(x, y) tests that x and y have the same names, and that x[names(y)] equals y.

Usage

expect_setequal(object, expected)

expect_mapequal(object, expected)

expect_contains(object, expected)

expect_in(object, expected)

Arguments

Details

Note that expect_setequal() ignores names, and you will be warned if both object and expected have them.

Examples

expect_setequal(letters, rev(letters))
show_failure(expect_setequal(letters[-1], rev(letters)))

x <- list(b = 2, a = 1)
expect_mapequal(x, list(a = 1, b = 2))
show_failure(expect_mapequal(x, list(a = 1)))
show_failure(expect_mapequal(x, list(a = 1, b = "x")))
show_failure(expect_mapequal(x, list(a = 1, b = 2, c = 3)))

Description

Checks that the code produces no output, messages, or warnings.

Usage

expect_silent(object)

Arguments

Value

The first argument, invisibly.

See Also

Other expectations: comparison-expectations, equality-expectations, expect_error(), expect_length(), expect_match(), expect_named(), expect_null(), expect_output(), expect_reference(), inheritance-expectations, logical-expectations

Examples

expect_silent("123")

f <- function() {
  message("Hi!")
  warning("Hey!!")
  print("OY!!!")
}
## Not run: 
expect_silent(f())

## End(Not run)

Description

Snapshot tests (aka golden tests) are similar to unit tests except that the expected result is stored in a separate file that is managed by testthat. Snapshot tests are useful for when the expected value is large, or when the intent of the code is something that can only be verified by a human (e.g. this is a useful error message). Learn more in vignette("snapshotting").

expect_snapshot() runs code as if you had executed it at the console, and records the results, including output, messages, warnings, and errors. If you just want to compare the result, try expect_snapshot_value().

Usage

expect_snapshot(
  x,
  cran = FALSE,
  error = FALSE,
  transform = NULL,
  variant = NULL,
  cnd_class = FALSE
)

Arguments

Workflow

The first time that you run a snapshot expectation it will run x, capture the results, and record them in ⁠tests/testthat/_snaps/{test}.md⁠. Each test file gets its own snapshot file, e.g. test-foo.R will get ⁠_snaps/foo.md⁠.

It's important to review the Markdown files and commit them to git. They are designed to be human readable, and you should always review new additions to ensure that the salient information has been captured. They should also be carefully reviewed in pull requests, to make sure that snapshots have updated in the expected way.

On subsequent runs, the result of x will be compared to the value stored on disk. If it's different, the expectation will fail, and a new file ⁠_snaps/{test}.new.md⁠ will be created. If the change was deliberate, you can approve the change with snapshot_accept() and then the tests will pass the next time you run them.

Note that snapshotting can only work when executing a complete test file (with test_file(), test_dir(), or friends) because there's otherwise no way to figure out the snapshot path. If you run snapshot tests interactively, they'll just display the current value.

Description

Whole file snapshot testing is designed for testing objects that don't have a convenient textual representation, with initial support for images (.png, .jpg, .svg), data frames (.csv), and text files (.R, .txt, .json, ...).

The first time expect_snapshot_file() is run, it will create ⁠_snaps/{test}/{name}.{ext}⁠ containing reference output. Future runs will be compared to this reference: if different, the test will fail and the new results will be saved in ⁠_snaps/{test}/{name}.new.{ext}⁠. To review failures, call snapshot_review().

We generally expect this function to be used via a wrapper that takes care of ensuring that output is as reproducible as possible, e.g. automatically skipping tests where it's known that images can't be reproduced exactly.

Usage

expect_snapshot_file(
  path,
  name = basename(path),
  binary = lifecycle::deprecated(),
  cran = FALSE,
  compare = NULL,
  transform = NULL,
  variant = NULL
)

announce_snapshot_file(path, name = basename(path))

compare_file_binary(old, new)

compare_file_text(old, new)

Arguments

Announcing snapshots

testthat automatically detects dangling snapshots that have been written to the ⁠_snaps⁠ directory but which no longer have corresponding R code to generate them. These dangling files are automatically deleted so they don't clutter the snapshot directory. However we want to preserve snapshot files when the R code wasn't executed because of an unexpected error or because of a skip(). Let testthat know about these files by calling announce_snapshot_file() before expect_snapshot_file().

Examples

# To use expect_snapshot_file() you'll typically need to start by writing
# a helper function that creates a file from your code, returning a path
save_png <- function(code, width = 400, height = 400) {
  path <- tempfile(fileext = ".png")
  png(path, width = width, height = height)
  on.exit(dev.off())
  code

  path
}
path <- save_png(plot(1:5))
path

## Not run: 
expect_snapshot_file(save_png(hist(mtcars$mpg)), "plot.png")

## End(Not run)

# You'd then also provide a helper that skips tests where you can't
# be sure of producing exactly the same output
expect_snapshot_plot <- function(name, code) {
  # Other packages might affect results
  skip_if_not_installed("ggplot2", "2.0.0")
  # Or maybe the output is different on some operation systems
  skip_on_os("windows")
  # You'll need to carefully think about and experiment with these skips

  name <- paste0(name, ".png")

  # Announce the file before touching `code`. This way, if `code`
  # unexpectedly fails or skips, testthat will not auto-delete the
  # corresponding snapshot file.
  announce_snapshot_file(name = name)

  path <- save_png(code)
  expect_snapshot_file(path, name)
}

Description

Captures the result of function, flexibly serializing it into a text representation that's stored in a snapshot file. See expect_snapshot() for more details on snapshot testing.

Usage

expect_snapshot_value(
  x,
  style = c("json", "json2", "deparse", "serialize"),
  cran = FALSE,
  tolerance = testthat_tolerance(),
  ...,
  variant = NULL
)

Arguments

Description

expect_vector() is a thin wrapper around vctrs::vec_assert(), converting the results of that function in to the expectations used by testthat. This means that it used the vctrs of ptype (prototype) and size. See details in https://vctrs.r-lib.org/articles/type-size.html

Usage

expect_vector(object, ptype = NULL, size = NULL)

Arguments

Examples

if (requireNamespace("vctrs") && packageVersion("vctrs") > "0.1.0.9002") {
expect_vector(1:10, ptype = integer(), size = 10)
show_failure(expect_vector(1:10, ptype = integer(), size = 5))
show_failure(expect_vector(1:10, ptype = character(), size = 5))
}

Description

These allow you to manually trigger success or failure. Failure is particularly useful to a pre-condition or mark a test as not yet implemented.

Usage

fail(
  message = "Failure has been forced",
  info = NULL,
  trace_env = caller_env()
)

succeed(message = "Success has been forced", info = NULL)

Arguments

Examples

## Not run: 
test_that("this test fails", fail())
test_that("this test succeeds", succeed())

## End(Not run)

Description

This reporter will simply throw an error if any of the tests failed. It is best combined with another reporter, such as the SummaryReporter.

See Also

Other reporters: CheckReporter, DebugReporter, JunitReporter, ListReporter, LocationReporter, MinimalReporter, MultiReporter, ProgressReporter, RStudioReporter, Reporter, SilentReporter, StopReporter, SummaryReporter, TapReporter, TeamcityReporter

Description

See https://adv-r.hadley.nz/oo.html for an overview of R's OO systems, and the vocabulary used here.

• expect_type(x, type) checks that typeof(x) is type.

• expect_s3_class(x, class) checks that x is an S3 object that inherits() from class

• expect_s3_class(x, NA) checks that x isn't an S3 object.

• expect_s4_class(x, class) checks that x is an S4 object that is() class.

• expect_s4_class(x, NA) checks that x isn't an S4 object.

See expect_vector() for testing properties of objects created by vctrs.

Usage

expect_type(object, type)

expect_s3_class(object, class, exact = FALSE)

expect_s4_class(object, class)

Arguments

See Also

Other expectations: comparison-expectations, equality-expectations, expect_error(), expect_length(), expect_match(), expect_named(), expect_null(), expect_output(), expect_reference(), expect_silent(), logical-expectations

Examples

x <- data.frame(x = 1:10, y = "x", stringsAsFactors = TRUE)
# A data frame is an S3 object with class data.frame
expect_s3_class(x, "data.frame")
show_failure(expect_s4_class(x, "data.frame"))
# A data frame is built from a list:
expect_type(x, "list")

# An integer vector is an atomic vector of type "integer"
expect_type(x$x, "integer")
# It is not an S3 object
show_failure(expect_s3_class(x$x, "integer"))

# Above, we requested data.frame() converts strings to factors:
show_failure(expect_type(x$y, "character"))
expect_s3_class(x$y, "factor")
expect_type(x$y, "integer")

Description

These functions help you determine if you code is running in a particular testing context:

• is_testing() is TRUE inside a test.

• is_snapshot() is TRUE inside a snapshot test

• is_checking() is TRUE inside of ⁠R CMD check⁠ (i.e. by test_check()).

• is_parallel() is TRUE if the tests are run in parallel.

• testing_package() gives name of the package being tested.

A common use of these functions is to compute a default value for a quiet argument with is_testing() && !is_snapshot(). In this case, you'll want to avoid an run-time dependency on testthat, in which case you should just copy the implementation of these functions into a utils.R or similar.

Usage

is_testing()

is_parallel()

is_checking()

is_snapshot()

testing_package()

Description

This reporter includes detailed results about each test and summaries, written to a file (or stdout) in jUnit XML format. This can be read by the Jenkins Continuous Integration System to report on a dashboard etc. Requires the xml2 package.

Details

To fit into the jUnit structure, context() becomes the ⁠<testsuite>⁠ name as well as the base of the ⁠<testcase> classname⁠. The test_that() name becomes the rest of the ⁠<testcase> classname⁠. The deparsed expect_that() call becomes the ⁠<testcase>⁠ name. On failure, the message goes into the ⁠<failure>⁠ node message argument (first line only) and into its text content (full message).

Execution time and some other details are also recorded.

References for the jUnit XML format: http://llg.cubic.org/docs/junit/

See Also

Other reporters: CheckReporter, DebugReporter, FailReporter, ListReporter, LocationReporter, MinimalReporter, MultiReporter, ProgressReporter, RStudioReporter, Reporter, SilentReporter, StopReporter, SummaryReporter, TapReporter, TeamcityReporter

Description

This reporter gathers all results, adding additional information such as test elapsed time, and test filename if available. Very useful for reporting.

See Also

Other reporters: CheckReporter, DebugReporter, FailReporter, JunitReporter, LocationReporter, MinimalReporter, MultiReporter, ProgressReporter, RStudioReporter, Reporter, SilentReporter, StopReporter, SummaryReporter, TapReporter, TeamcityReporter

Description

with_mocked_bindings() and local_mocked_bindings() provide tools for "mocking", temporarily redefining a function so that it behaves differently during tests. This is helpful for testing functions that depend on external state (i.e. reading a value from a file or a website, or pretending a package is or isn't installed).

These functions represent a second attempt at bringing mocking to testthat, incorporating what we've learned from the mockr, mockery, and mockthat packages.

Usage

local_mocked_bindings(..., .package = NULL, .env = caller_env())

with_mocked_bindings(code, ..., .package = NULL)

Arguments

Use

There are four places that the function you are trying to mock might come from:

• Internal to your package.

• Imported from an external package via the NAMESPACE.

• The base environment.

• Called from an external package with ::.

They are described in turn below.

Internal & imported functions

You mock internal and imported functions the same way. For example, take this code:

some_function <- function() {
  another_function()
}

It doesn't matter whether another_function() is defined by your package or you've imported it from a dependency with ⁠@import⁠ or ⁠@importFrom⁠, you mock it the same way:

local_mocked_bindings(
  another_function = function(...) "new_value"
)

Base functions

To mock a function in the base package, you need to make sure that you have a binding for this function in your package. It's easiest to do this by binding the value to NULL. For example, if you wanted to mock interactive() in your package, you'd need to include this code somewhere in your package:

interactive <- NULL

Why is this necessary? with_mocked_bindings() and local_mocked_bindings() work by temporarily modifying the bindings within your package's namespace. When these tests are running inside of ⁠R CMD check⁠ the namespace is locked which means it's not possible to create new bindings so you need to make sure that the binding exists already.

Namespaced calls

It's trickier to mock functions in other packages that you call with ::. For example, take this minor variation:

some_function <- function() {
  anotherpackage::another_function()
}

To mock this function, you'd need to modify another_function() inside the anotherpackage package. You can do this by supplying the .package argument to local_mocked_bindings() but we don't recommend it because it will affect all calls to anotherpackage::another_function(), not just the calls originating in your package. Instead, it's safer to either import the function into your package, or make a wrapper that you can mock:

some_function <- function() {
  my_wrapper()
}
my_wrapper <- function(...) {
  anotherpackage::another_function(...)
}

local_mocked_bindings(
  my_wrapper = function(...) "new_value"
)

Description

local_test_context() is run automatically by test_that() but you may want to run it yourself if you want to replicate test results interactively. If run inside a function, the effects are automatically reversed when the function exits; if running in the global environment, use withr::deferred_run() to undo.

local_reproducible_output() is run automatically by test_that() in the 3rd edition. You might want to call it to override the the default settings inside a test, if you want to test Unicode, coloured output, or a non-standard width.

Usage

local_test_context(.env = parent.frame())

local_reproducible_output(
  width = 80,
  crayon = FALSE,
  unicode = FALSE,
  rstudio = FALSE,
  hyperlinks = FALSE,
  lang = "en",
  .env = parent.frame()
)

Arguments

Details

local_test_context() sets TESTTHAT = "true", which ensures that is_testing() returns TRUE and allows code to tell if it is run by testthat.

In the third edition, local_test_context() also calls local_reproducible_output() which temporary sets the following options:

• cli.dynamic = FALSE so that tests assume that they are not run in a dynamic console (i.e. one where you can move the cursor around).

• cli.unicode (default: FALSE) so that the cli package never generates unicode output (normally cli uses unicode on Linux/Mac but not Windows). Windows can't easily save unicode output to disk, so it must be set to false for consistency.

• cli.condition_width = Inf so that new lines introduced while width-wrapping condition messages don't interfere with message matching.

• crayon.enabled (default: FALSE) suppresses ANSI colours generated by the cli and crayon packages (normally colours are used if cli detects that you're in a terminal that supports colour).

• cli.num_colors (default: 1L) Same as the crayon option.

• lifecycle_verbosity = "warning" so that every lifecycle problem always generates a warning (otherwise deprecated functions don't generate a warning every time).

• max.print = 99999 so the same number of values are printed.

• OutDec = "." so numbers always uses . as the decimal point (European users sometimes set OutDec = ",").

• rlang_interactive = FALSE so that rlang::is_interactive() returns FALSE, and code that uses it pretends you're in a non-interactive environment.

• useFancyQuotes = FALSE so base R functions always use regular (straight) quotes (otherwise the default is locale dependent, see sQuote() for details).

• width (default: 80) to control the width of printed output (usually this varies with the size of your console).

And modifies the following env vars:

• Unsets RSTUDIO, which ensures that RStudio is never detected as running.

• Sets LANGUAGE = "en", which ensures that no message translation occurs.

Finally, it sets the collation locale to "C", which ensures that character sorting the same regardless of system locale.

Examples

local({
  local_test_context()
  cat(cli::col_blue("Text will not be colored"))
  cat(cli::symbol$ellipsis)
  cat("\n")
})
test_that("test ellipsis", {
  local_reproducible_output(unicode = FALSE)
  expect_equal(cli::symbol$ellipsis, "...")

  local_reproducible_output(unicode = TRUE)
  expect_equal(cli::symbol$ellipsis, "\u2026")
})

Description

This reporter simply prints the location of every expectation and error. This is useful if you're trying to figure out the source of a segfault, or you want to figure out which code triggers a C/C++ breakpoint

See Also

Other reporters: CheckReporter, DebugReporter, FailReporter, JunitReporter, ListReporter, MinimalReporter, MultiReporter, ProgressReporter, RStudioReporter, Reporter, SilentReporter, StopReporter, SummaryReporter, TapReporter, TeamcityReporter

Description

These are fall-back expectations that you can use when none of the other more specific expectations apply. The disadvantage is that you may get a less informative error message.

Usage

expect_true(object, info = NULL, label = NULL)

expect_false(object, info = NULL, label = NULL)

Arguments

Details

Attributes are ignored.

See Also

is_false() for complement

Other expectations: comparison-expectations, equality-expectations, expect_error(), expect_length(), expect_match(), expect_named(), expect_null(), expect_output(), expect_reference(), expect_silent(), inheritance-expectations

Examples

expect_true(2 == 2)
# Failed expectations will throw an error
## Not run: 
expect_true(2 != 2)

## End(Not run)
expect_true(!(2 != 2))
# or better:
expect_false(2 != 2)

a <- 1:3
expect_true(length(a) == 3)
# but better to use more specific expectation, if available
expect_equal(length(a), 3)

Description

The minimal test reporter provides the absolutely minimum amount of information: whether each expectation has succeeded, failed or experienced an error. If you want to find out what the failures and errors actually were, you'll need to run a more informative test reporter.

See Also

Other reporters: CheckReporter, DebugReporter, FailReporter, JunitReporter, ListReporter, LocationReporter, MultiReporter, ProgressReporter, RStudioReporter, Reporter, SilentReporter, StopReporter, SummaryReporter, TapReporter, TeamcityReporter

Description

This reporter is useful to use several reporters at the same time, e.g. adding a custom reporter without removing the current one.

See Also

Other reporters: CheckReporter, DebugReporter, FailReporter, JunitReporter, ListReporter, LocationReporter, MinimalReporter, ProgressReporter, RStudioReporter, Reporter, SilentReporter, StopReporter, SummaryReporter, TapReporter, TeamcityReporter

Description

ProgressReporter is designed for interactive use. Its goal is to give you actionable insights to help you understand the status of your code. This reporter also praises you from time-to-time if all your tests pass. It's the default reporter for test_dir().

ParallelProgressReporter is very similar to ProgressReporter, but works better for packages that want parallel tests.

CompactProgressReporter is a minimal version of ProgressReporter designed for use with single files. It's the default reporter for test_file().

See Also

Other reporters: CheckReporter, DebugReporter, FailReporter, JunitReporter, ListReporter, LocationReporter, MinimalReporter, MultiReporter, RStudioReporter, Reporter, SilentReporter, StopReporter, SummaryReporter, TapReporter, TeamcityReporter

Description

This reporter is designed for output to RStudio. It produces results in any easily parsed form.

See Also

Other reporters: CheckReporter, DebugReporter, FailReporter, JunitReporter, ListReporter, LocationReporter, MinimalReporter, MultiReporter, ProgressReporter, Reporter, SilentReporter, StopReporter, SummaryReporter, TapReporter, TeamcityReporter

Description

One of the most pernicious challenges to debug is when a test runs fine in your test suite, but fails when you run it interactively (or similarly, it fails randomly when running your tests in parallel). One of the most common causes of this problem is accidentally changing global state in a previous test (e.g. changing an option, an environment variable, or the working directory). This is hard to debug, because it's very hard to figure out which test made the change.

Luckily testthat provides a tool to figure out if tests are changing global state. You can register a state inspector with set_state_inspector() and testthat will run it before and after each test, store the results, then report if there are any differences. For example, if you wanted to see if any of your tests were changing options or environment variables, you could put this code in tests/testthat/helper-state.R:

set_state_inspector(function() {
  list(
    options = options(),
    envvars = Sys.getenv()
  )
})

(You might discover other packages outside your control are changing the global state, in which case you might want to modify this function to ignore those values.)

Other problems that can be troublesome to resolve are CRAN check notes that report things like connections being left open. You can easily debug that problem with:

set_state_inspector(function() {
  getAllConnections()
})

Usage

set_state_inspector(callback)

Arguments

Description

This reporter quietly runs all tests, simply gathering all expectations. This is helpful for programmatically inspecting errors after a test run. You can retrieve the results with the expectations() method.

See Also

Other reporters: CheckReporter, DebugReporter, FailReporter, JunitReporter, ListReporter, LocationReporter, MinimalReporter, MultiReporter, ProgressReporter, RStudioReporter, Reporter, StopReporter, SummaryReporter, TapReporter, TeamcityReporter

Description

skip_if() and skip_if_not() allow you to skip tests, immediately concluding a test_that() block without executing any further expectations. This allows you to skip a test without failure, if for some reason it can't be run (e.g. it depends on the feature of a specific operating system, or it requires a specific version of a package).

See vignette("skipping") for more details.

Usage

skip(message = "Skipping")

skip_if_not(condition, message = NULL)

skip_if(condition, message = NULL)

skip_if_not_installed(pkg, minimum_version = NULL)

skip_if_offline(host = "captive.apple.com")

skip_on_cran()

skip_on_os(os, arch = NULL)

skip_on_ci()

skip_on_covr()

skip_on_bioc()

skip_if_translated(msgid = "'%s' not found")

Arguments

Helpers

• skip_if_not_installed("pkg") skips tests if package "pkg" is not installed or cannot be loaded (using requireNamespace()). Generally, you can assume that suggested packages are installed, and you do not need to check for them specifically, unless they are particularly difficult to install.

• skip_if_offline() skips if an internet connection is not available (using curl::nslookup()) or if the test is run on CRAN. Requires the curl packages to be installed.

• skip_if_translated("msg") skips tests if the "msg" is translated.

• skip_on_bioc() skips on Bioconductor (using the IS_BIOC_BUILD_MACHINE env var).

• skip_on_cran() skips on CRAN (using the NOT_CRAN env var set by devtools and friends).

• skip_on_covr() skips when covr is running (using the R_COVR env var).

• skip_on_ci() skips on continuous integration systems like GitHub Actions, travis, and appveyor (using the CI env var).

• skip_on_os() skips on the specified operating system(s) ("windows", "mac", "linux", or "solaris").

Examples

if (FALSE) skip("Some Important Requirement is not available")

test_that("skip example", {
  expect_equal(1, 1L)    # this expectation runs
  skip('skip')
  expect_equal(1, 2)     # this one skipped
  expect_equal(1, 3)     # this one is also skipped
})

Description

• snapshot_accept() accepts all modified snapshots.

• snapshot_review() opens a Shiny app that shows a visual diff of each modified snapshot. This is particularly useful for whole file snapshots created by expect_snapshot_file().

Usage

snapshot_accept(files = NULL, path = "tests/testthat")

snapshot_review(files = NULL, path = "tests/testthat")

Arguments

Description

The default reporter used when expect_that() is run interactively. It responds by stop()ping on failures and doing nothing otherwise. This will ensure that a failing test will raise an error.

Details

This should be used when doing a quick and dirty test, or during the final automated testing of R CMD check. Otherwise, use a reporter that runs all tests and gives you more context about the problem.

See Also

Other reporters: CheckReporter, DebugReporter, FailReporter, JunitReporter, ListReporter, LocationReporter, MinimalReporter, MultiReporter, ProgressReporter, RStudioReporter, Reporter, SilentReporter, SummaryReporter, TapReporter, TeamcityReporter

Description

This is a reporter designed for interactive usage: it lets you know which tests have run successfully and as well as fully reporting information about failures and errors.

Details

You can use the max_reports field to control the maximum number of detailed reports produced by this reporter. This is useful when running with auto_test()

As an additional benefit, this reporter will praise you from time-to-time if all your tests pass.

See Also

Other reporters: CheckReporter, DebugReporter, FailReporter, JunitReporter, ListReporter, LocationReporter, MinimalReporter, MultiReporter, ProgressReporter, RStudioReporter, Reporter, SilentReporter, StopReporter, TapReporter, TeamcityReporter

Description

This reporter will output results in the Test Anything Protocol (TAP), a simple text-based interface between testing modules in a test harness. For more information about TAP, see http://testanything.org

See Also

Other reporters: CheckReporter, DebugReporter, FailReporter, JunitReporter, ListReporter, LocationReporter, MinimalReporter, MultiReporter, ProgressReporter, RStudioReporter, Reporter, SilentReporter, StopReporter, SummaryReporter, TeamcityReporter

Description

This reporter will output results in the Teamcity message format. For more information about Teamcity messages, see http://confluence.jetbrains.com/display/TCD7/Build+Script+Interaction+with+TeamCity

See Also

Other reporters: CheckReporter, DebugReporter, FailReporter, JunitReporter, ListReporter, LocationReporter, MinimalReporter, MultiReporter, ProgressReporter, RStudioReporter, Reporter, SilentReporter, StopReporter, SummaryReporter, TapReporter

Description

This environment has no purpose other than as a handle for withr::defer(): use it when you want to run code after all tests have been run. Typically, you'll use withr::defer(cleanup(), teardown_env()) immediately after you've made a mess in a ⁠setup-*.R⁠ file.

Usage

teardown_env()

Description

Helper, setup, and teardown files located in the same directory as the test will also be run. See vignette("special-files") for details.

Usage

test_file(
  path,
  reporter = default_compact_reporter(),
  desc = NULL,
  package = NULL,
  ...
)

Arguments

Value

A list (invisibly) containing data about the test results.

Environments

Each test is run in a clean environment to keep tests as isolated as possible. For package tests, that environment inherits from the package's namespace environment, so that tests can access internal functions and objects.

Examples

path <- testthat_example("success")
test_file(path)
test_file(path, desc = "some tests have warnings")
test_file(path, reporter = "minimal")

Description

• test_local() tests a local source package.

• test_package() tests an installed package.

• test_check() checks a package during ⁠R CMD check⁠.

See vignette("special-files") to learn about the various files that testthat works with.

Usage

test_package(package, reporter = check_reporter(), ...)

test_check(package, reporter = check_reporter(), ...)

test_local(path = ".", reporter = NULL, ..., load_package = "source")

Arguments

Value

A list (invisibly) containing data about the test results.

⁠R CMD check⁠

To run testthat automatically from ⁠R CMD check⁠, make sure you have a tests/testthat.R that contains:

library(testthat)
library(yourpackage)

test_check("yourpackage")

Environments

Each test is run in a clean environment to keep tests as isolated as possible. For package tests, that environment inherits from the package's namespace environment, so that tests can access internal functions and objects.

Description

Many tests require some external file (e.g. a .csv if you're testing a data import function) but the working directory varies depending on the way that you're running the test (e.g. interactively, with devtools::test(), or with ⁠R CMD check⁠). test_path() understands these variations and automatically generates a path relative to tests/testthat, regardless of where that directory might reside relative to the current working directory.

Usage

test_path(...)

Arguments

Value

A character vector giving the path.

Examples

## Not run: 
test_path("foo.csv")
test_path("data", "foo.csv")

## End(Not run)

Description

A test encapsulates a series of expectations about a small, self-contained unit of functionality. Each test contains one or more expectations, such as expect_equal() or expect_error(), and lives in a ⁠test/testhat/test*⁠ file, often together with other tests that relate to the same function or set of functions.

Each test has its own execution environment, so an object created in a test also dies with the test. Note that this cleanup does not happen automatically for other aspects of global state, such as session options or filesystem changes. Avoid changing global state, when possible, and reverse any changes that you do make.

Usage

test_that(desc, code)

Arguments

Value

When run interactively, returns invisible(TRUE) if all tests pass, otherwise throws an error.

Examples

test_that("trigonometric functions match identities", {
  expect_equal(sin(pi / 4), 1 / sqrt(2))
  expect_equal(cos(pi / 4), 1 / sqrt(2))
  expect_equal(tan(pi / 4), 1)
})

## Not run: 
test_that("trigonometric functions match identities", {
  expect_equal(sin(pi / 4), 1)
})

## End(Not run)

Description

Add the necessary infrastructure to enable C++ unit testing in R packages with Catch and testthat.

Usage

use_catch(dir = getwd())

Arguments

Details

Calling use_catch() will:

1. Create a file src/test-runner.cpp, which ensures that the testthat package will understand how to run your package's unit tests,

2. Create an example test file src/test-example.cpp, which showcases how you might use Catch to write a unit test,

3. Add a test file tests/testthat/test-cpp.R, which ensures that testthat will run your compiled tests during invocations of devtools::test() or ⁠R CMD check⁠, and

4. Create a file R/catch-routine-registration.R, which ensures that R will automatically register this routine when tools::package_native_routine_registration_skeleton() is invoked.

You will also need to:

• Add xml2 to Suggests, with e.g. usethis::use_package("xml2", "Suggests")

• Add testthat to LinkingTo, with e.g. usethis::use_package("testthat", "LinkingTo")

C++ unit tests can be added to C++ source files within the src directory of your package, with a format similar to R code tested with testthat. Here's a simple example of a unit test written with testthat + Catch:

context("C++ Unit Test") {
  test_that("two plus two is four") {
    int result = 2 + 2;
    expect_true(result == 4);
  }
}

When your package is compiled, unit tests alongside a harness for running these tests will be compiled into your R package, with the C entry point run_testthat_tests(). testthat will use that entry point to run your unit tests when detected.

Functions

All of the functions provided by Catch are available with the CATCH_ prefix – see here for a full list. testthat provides the following wrappers, to conform with testthat's R interface:

In general, you should prefer using the testthat wrappers, as testthat also does some work to ensure that any unit tests within will not be compiled or run when using the Solaris Studio compilers (as these are currently unsupported by Catch). This should make it easier to submit packages to CRAN that use Catch.

Symbol Registration

If you've opted to disable dynamic symbol lookup in your package, then you'll need to explicitly export a symbol in your package that testthat can use to run your unit tests. testthat will look for a routine with one of the names:

    C_run_testthat_tests
    c_run_testthat_tests
    run_testthat_tests

See Controlling Visibility and Registering Symbols in the Writing R Extensions manual for more information.

Advanced Usage

If you'd like to write your own Catch test runner, you can instead use the testthat::catchSession() object in a file with the form:

#define TESTTHAT_TEST_RUNNER
#include <testthat.h>

void run()
{
    Catch::Session& session = testthat::catchSession();
    // interact with the session object as desired
}

This can be useful if you'd like to run your unit tests with custom arguments passed to the Catch session.

Standalone Usage

If you'd like to use the C++ unit testing facilities provided by Catch, but would prefer not to use the regular testthat R testing infrastructure, you can manually run the unit tests by inserting a call to:

.Call("run_testthat_tests", PACKAGE = <pkgName>)

as necessary within your unit test suite.

See Also

Catch, the library used to enable C++ unit testing.