Does code print output to the console?

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

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.

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)
#> 'data.frame':	32 obs. of  11 variables:
#>  $ mpg : num  21 21 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 ...
#>  $ cyl : num  6 6 4 6 8 6 8 4 4 6 ...
#>  $ disp: num  160 160 108 258 360 ...
#>  $ hp  : num  110 110 93 110 175 105 245 62 95 123 ...
#>  $ drat: num  3.9 3.9 3.85 3.08 3.15 2.76 3.21 3.69 3.92 3.92 ...
#>  $ wt  : num  2.62 2.88 2.32 3.21 3.44 ...
#>  $ qsec: num  16.5 17 18.6 19.4 17 ...
#>  $ vs  : num  0 0 1 1 0 1 0 1 1 1 ...
#>  $ am  : num  1 1 1 0 0 0 0 0 0 0 ...
#>  $ gear: num  4 4 4 3 3 3 3 4 4 4 ...
#>  $ carb: num  4 4 1 1 2 1 4 2 2 4 ...
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)