expect_output: Does code print output to the console?

In testthat: Unit Testing for R

Does code print output to the console?

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

object	Object to test. Supports limited unquoting to make it easier to generate readable failures within a function or for loop. See quasi_label for more details.
regexp	Regular expression to test against. A character vector giving a regular expression that must match the output. If NULL, the default, asserts that there should output, but doesn't check for a specific value. If NA, asserts that there should be no output.
...	Arguments passed on to expect_match all Should all elements of actual value match regexp (TRUE), or does only one need to match (FALSE). fixed If TRUE, treats regexp as a string to be matched exactly (not a regular expressions). Overrides perl. perl logical. Should Perl-compatible regexps be used?
info	Extra information to be included in the message. This argument is soft-deprecated and should not be used in new code. Instead see alternatives in quasi_label.
label	Used to customise failure messages. For expert use only.
width	Number of characters per line of output. This does not inherit from getOption("width") so that tests always use the same output width, minimising spurious differences.

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)

testthat documentation built on May 29, 2024, 9:38 a.m.