Validate that certain conditions are true.

validate_that is an alternative to the function assert_that, that returns a character vector. This makes them easier to use within S4 "validate" methods.

validate_that(..., env = parent.frame(), msg = NULL)

Arguments

...

unnamed expressions that describe the conditions to be tested. Rather than combining expressions with &&, separate them by commas so that better error messages can be generated.

env

(advanced use only) the environment in which to evaluate the assertions.

msg

a custom error message to be printed if one of the conditions is false.

Value

A character vector if the assertion is false, or TRUE if the assertion is true.

See also

assert_that, which returns an error if the condition is false.

Examples

x <- 1
# assert_that() generates errors, so can't be usefully run in
# examples
validate_that(is.numeric(x))
#> [1] TRUE
validate_that(is.character(x))
#> [1] "x is not a character vector"
validate_that(length(x) == 3)
#> [1] "length(x) not equal to 3"
validate_that(is.dir("asdf"))
#> [1] "Path 'asdf' does not exist"