added checking

NAMESPACE

@@ -17,6 +17,7 @@ export(ard_ttest)
 export(ard_wilcoxtest)
 export(as_nested_list)
 export(bind_ard)
+export(check_list_elements)
 export(compute_formula_selector)
 export(contains)
 export(continuous_variable_summary_fns)

R/ard_continuous.R

@@ -51,6 +51,13 @@ ard_continuous <- function(data,
   data <- dplyr::ungroup(data)
   process_selectors(data, variables = {{variables}}, by = {{by}}, strata = {{strata}})
   process_formula_selectors(data = data[variables], statistics = statistics)
+  check_list_elements(
+    statistics = function(x) is.list(x) && rlang::is_named(x) && every(x, is.function),
+    error_msg =
+      list(statistics =
+             c("Error in the argument {.arg {arg_name}} for variable {.val {variable}}.",
+               "i" = "Value must be a named list of functions."))
+  )
 
   # return empty tibble if no variables selected -------------------------------
   if (rlang::is_empty(variables)) return(dplyr::tibble())

R/process_selectors.R

@@ -12,19 +12,31 @@
 #'   function processes these inputs and returns a named list. If an name is
 #'   repeated, the last entry is kept.
 #'
-#' - `compute_formula_selector()`:
+#' - `compute_formula_selector()`: used in `process_formula_selectors()` to
+#'   evaluate a single argument.
+#'
+#' - `check_list_elements()`: accepts named arguments where the name is a list
+#'   that exists in the env, and the argument value is a predicate function
+#'   used to the values of the list.
 #'
 #' @param data a data frame
 #' @param ... named arguments where the value of the argument is processed with tidyselect.
 #' - `process_selectors()`: the values are tidyselect-compatible selectors
 #' - `process_formula_selectors()`: the values are named lists, list of formulas
 #'   a combination of both, or a single formula. Users may pass `~value` as a
 #'   shortcut for `everything() ~ value`.
+#' - `check_list_elements()`: named arguments where the name matches an existing
+#'   list in the `env` environment, and the value is a predicate function
+#'   to test each element of the list, e.g. each element must be a string or
+#'   a function.
 #' @param env env to save the results to. Default is the calling environment.
 #' @param x a named list, list of formulas, or a single formula that will be
 #' converted to a named list.
 #' @param arg_name a string with the argument named being processed. Used
 #' in error messaging.
+#' @param error_msg a named list where the list elements are strings that will
+#' be used in error messaging when mis-specified arguments are passed. Elements
+#' `"{arg_name}"` and `"{variable}"` are available using glue syntax for messaging.
 #'
 #' @name process_selectors
 #'
@@ -132,3 +144,28 @@ compute_formula_selector <- function(data, x, arg_name = '', env = rlang::caller
 }
 
 
+#' @name process_selectors
+#' @export
+check_list_elements <- function(..., error_msg = list(), env = rlang::caller_env()) {
+  dots <- rlang::dots_list(...)
+
+  imap(
+    dots,
+    function(predicate_fn, arg_name) {
+      imap(
+        get(arg_name, envir = env),
+        function(lst_element, variable) {
+          if (!isTRUE(predicate_fn(lst_element))) {
+            msg <-
+              error_msg[[arg_name]] %||%
+              "The value for argument {.arg {arg_name}} and variable {.val {variable}} is not the expected type."
+            cli::cli_abort(message = msg)
+          }
+        }
+      )
+    }
+  )
+
+  invisible()
+}
+

inst/WORDLIST

@@ -26,6 +26,7 @@ env
 esult
 ets
 funder
+mis
 nalysis
 nonmiss
 quosures

tests/testthat/_snaps/ard_continuous.md

@@ -0,0 +1,9 @@
+# ard_continuous() messaging
+
+    Code
+      ard_continuous(mtcars, variables = "mpg", statistics = ~ list(mean = "this is a string"))
+    Condition
+      Error:
+      ! Error in the argument `statistics` for variable "mpg".
+      i Value must be a named list of functions.
+

tests/testthat/test-ard_continuous.R

@@ -1,4 +1,4 @@
-test_that("multiplication works", {
+test_that("ard_continuous() works", {
   expect_error(
     ard_test <-
       ard_continuous(mtcars, variables = c(mpg, hp), by = c(am, vs)),
@@ -26,3 +26,13 @@ test_that("multiplication works", {
     dplyr::tibble()
   )
 })
+
+test_that("ard_continuous() messaging", {
+  # proper error message when statistics argument mis-specified
+  expect_snapshot(
+    ard_continuous(mtcars, variables = "mpg", statistics = ~list(mean = "this is a string")),
+    error = TRUE
+  )
+
+})
+