R/assert_no_globals.R

In IBAHCM/RPiR: Reproducible Programming in R

#' Assert that a function contains no global variables
#'
#' This function will stop code execution with an error if the function
#' passed in uses a global variable.
#'
#' @param test_function function to check for global variables
#' @param name (optional) the name of function as a string -- passed to the
#' error message
#'
#' @return nothing
#' @export
#'
#' @examples
#' \dontrun{
#' broken_function <- function() print(y)
#' assert_no_globals(broken_function)
#' assert_no_globals(broken_function, name = "the_name_of_my_function")
#' }
#'
assert_no_globals <- function(test_function,
                              name = deparse1(substitute(test_function))) {

  globals <- codetools::findGlobals(test_function, merge = FALSE)$variables
  message <- paste0("Function ", name, "() may not use global variable(s): ",
                    globals)

  if (length(globals) != 0) {
    stop(message)
  }

  NULL
}