Assert that the input is NULL — assert_null • assertions

This function asserts that the input is NULL and aborts with an error message if it is not.

Usage

assert_null(x, msg = NULL, call = rlang::caller_env(), arg_name = NULL)

Arguments

x: A value to check.
msg: A character string containing the error message to display if x is not NULL.
call: Only relevant when pooling assertions into multi-assertion helper functions. See cli_abort for details.
arg_name: Advanced use only. Name of the argument passed (default: NULL, will automatically extract arg_name).

Value

invisible(TRUE) if x is NULL, otherwise aborts with the error message specified by msg.

Examples

assert_null(NULL)  # Passes

try({
 assert_null(1)  # Throws default error
 assert_null(1, msg = "Custom error message")  # Throws custom error
})
#> Error in eval(expr, envir) : '1' must be NULL!