Turn a Check into an Expectation

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).

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.

See also

Other CustomConstructors: makeAssertion(), makeTest()

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)
#> function (x, info = NULL, label = vname(x)) 
#> {
#>     if (missing(x)) 
#>         stop(sprintf("Argument '%s' is missing", label))
#>     res = checkFalse(x)
#>     makeExpectation(x, res, info, label)
#> }
#> <environment: 0x7fb843782790>