R: Expectation: does code produce output/message/warning/error?

output-expectations {testthat}

R Documentation

Expectation: does code produce output/message/warning/error?

Description

Use expect_output(), expect_message() and expect_warning() to match specified outputs. Use expect_error() or expect_condition() to match individual errors or conditions. Use expect_silent() to assert that there should be no output of any type.

Usage

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

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

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

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

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

expect_silent(object)

Arguments

`object`	object to test
`regexp`	regular expression to test against. If `NULL`, the default, asserts that there should be an output, a messsage, a warning, or an error, but does not test for specific value. If `NA`, asserts that there should be no output, messages, warnings, or errors.
`...`	Arguments passed on to `expect_match` all Should all elements of actual value match `regexp` (TRUE), or does only one need to match (FALSE) perl logical. Should Perl-compatible regexps be used? fixed logical. If `TRUE`, `pattern` is a string to be matched as is. Overrides all conflicting arguments.
`info`	extra information to be included in the message (useful when writing tests in loops).
`label`	object label. When `NULL`, computed from deparsed object.
`class`	Instead of supplying a regular expression, you can also supply a class name. This is useful for "classed" conditions.
`all`	For messages and warnings, do all need to match the `regexp` (TRUE), or does only one need to match (FALSE)

Details

Note that warnings are captured by a custom signal handler: this means that options(warn) has no effect.

Value

The first argument, invisibly. If expect_error() captures an error, that is returned instead of the value.

Examples

# Output --------------------------------------------------------------------
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)

# Messages ------------------------------------------------------------------

f <- function(x) {
  if (x < 0) message("*x* is already negative")
  -x
}
expect_message(f(-1))
expect_message(f(-1), "already negative")
expect_message(f(1), NA)

# You can use the arguments of grepl to control the matching
expect_message(f(-1), "*x*", fixed = TRUE)
expect_message(f(-1), "NEGATIVE", ignore.case = TRUE)

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

# You can use the arguments of grepl to control the matching
expect_warning(f(-1), "*x*", fixed = TRUE)
expect_warning(f(-1), "NEGATIVE", ignore.case = TRUE)

# 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)

# Silent --------------------------------------------------------------------
expect_silent("123")

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

## End(Not run)

[Package testthat version 2.0.0 Index]