expect_match: Do you expect a string to match this pattern?

In testthat: Unit Testing for R

Do you expect a string to match this pattern?

Description

Do you expect a string to match this pattern?

Usage

expect_match(
  object,
  regexp,
  perl = FALSE,
  fixed = FALSE,
  ...,
  all = TRUE,
  info = NULL,
  label = NULL
)

expect_no_match(
  object,
  regexp,
  perl = FALSE,
  fixed = FALSE,
  ...,
  all = TRUE,
  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.
perl	logical. Should Perl-compatible regexps be used?
fixed	If TRUE, treats regexp as a string to be matched exactly (not a regular expressions). Overrides perl.
...	Arguments passed on to base::grepl ignore.case logical. if FALSE, the pattern matching is case sensitive and if TRUE, case is ignored during matching. useBytes logical. If TRUE the matching is done byte-by-byte rather than character-by-character. See ‘Details’.
all	Should all elements of actual value match 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.

Details

expect_match() checks if a character vector matches a regular expression, powered by grepl().

expect_no_match() provides the complementary case, checking that a character vector does not match a regular expression.

Functions

• expect_no_match(): Check that a string doesn't match a regular expression.

See Also

Other expectations: comparison-expectations, equality-expectations, expect_error(), expect_length(), expect_named(), expect_null(), expect_output(), expect_reference(), expect_silent(), inheritance-expectations, logical-expectations

Examples

expect_match("Testing is fun", "fun")
expect_match("Testing is fun", "f.n")
expect_no_match("Testing is fun", "horrible")

show_failure(expect_match("Testing is fun", "horrible"))
show_failure(expect_match("Testing is fun", "horrible", fixed = TRUE))

# Zero-length inputs always fail
show_failure(expect_match(character(), "."))

testthat documentation built on Nov. 25, 2025, 5:09 p.m.