expect: The previous building block of all 'expect_' functions

In testthat: Unit Testing for R

The previous building block of all expect_ functions

Description

Previously, we recommended using expect() when writing your own expectations. Now we instead recommend pass() and fail(). See vignette("custom-expectation") for details.

Usage

expect(
  ok,
  failure_message,
  info = NULL,
  srcref = NULL,
  trace = NULL,
  trace_env = caller_env()
)

Arguments

ok	TRUE or FALSE indicating if the expectation was successful.
failure_message	A character vector describing the failure. The first element should describe the expected value, and the second (and optionally subsequence) elements should describe what was actually seen.
info	Character vector continuing additional information. Included for backward compatibility only and new expectations should not use it.
srcref	Location of the failure. Should only needed to be explicitly supplied when you need to forward a srcref captured elsewhere.
trace	An optional backtrace created by rlang::trace_back(). When supplied, the expectation is displayed with the backtrace. Expert use only.
trace_env	If trace is not specified, this is used to generate an informative traceback for failures. You should only need to set this if you're calling fail() from a helper function; see vignette("custom-expectation") for details.

Value

An expectation object from either succeed() or fail(). with a muffle_expectation restart.

See Also

exp_signal()

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