makeExpectation: Turn a Check into an Expectation
In checkmate: Fast and Versatile Argument Checks

makeExpectation

R Documentation

Turn a Check into an Expectation

Description

makeExpectation is the internal function used to evaluate the result of a check and turn it into an expectation. makeExceptionFunction can be used to automatically create an expectation function based on a check function (see example).

Usage

makeExpectation(x, res, info, label)

makeExpectationFunction(
  check.fun,
  c.fun = NULL,
  use.namespace = FALSE,
  env = parent.frame()
)

Arguments

`x`	[`any`] Object to check.
`res`	[`TRUE` \| `character(1)`] The result of a check function: `TRUE` for successful checks, and an error message as string otherwise.
`info`	[`character(1)`] See `expect_that`
`label`	[`character(1)`] See `expect_that`
`check.fun`	[`function`] Function which checks the input. Must return `TRUE` on success and a string with the error message otherwise.
`c.fun`	[`character(1)`] If not `NULL`, instead of calling the function `check.fun`, use `.Call` to call a C function “c.fun” with the identical set of parameters. The C function must be registered as a native symbol, see `.Call`. Useful if `check.fun` is just a simple wrapper.
`use.namespace`	[`logical(1)`] Call functions of checkmate using its namespace explicitly. Can be set to `FALSE` so save some microseconds, but the checkmate package needs to be imported. Default is `TRUE`.
`env`	[`environment`] The environment of the created function. Default is the `parent.frame`.

Value

makeExpectation invisibly returns the checked object. makeExpectationFunction returns a function.

Examples

# Simple custom check function
checkFalse = function(x) if (!identical(x, FALSE)) "Must be FALSE" else TRUE

# Create the respective expect function
expect_false = function(x, info = NULL, label = vname(x)) {
  res = checkFalse(x)
  makeExpectation(x, res, info = info, label = label)
}

# Alternative: Automatically create such a function
expect_false = makeExpectationFunction(checkFalse)
print(expect_false)

checkmate documentation built on Aug. 18, 2025, 5:36 p.m.