expect_output: Expectation: 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 verify_output().

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)
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. 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.

Examples

Run this code

# NOT RUN {
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)
# }

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