testthat (version 2.3.2)

expect_message: Expectation: does code produce warnings or messages?

Description

Use expect_message() and expect_warning() to check if the messages or warnings match the given regular expression.

Usage

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

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 message/warning

• If NULL, the default, asserts that there should be a messsage/warning, but doesn't test for a specific value.

• If NA, asserts that there shouldn't be any messages or warnings.

...

Arguments passed on to expect_match

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.

all

Do messages/warnings need to match the regexp (TRUE), or does only one need to match (FALSE)?

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.

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_silent(), inheritance-expectations, logical-expectations

Examples

# NOT RUN {
# 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)

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

# 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")
    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)

# 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)

# }