Updated examples in add_p.tbl_continuous() (#2073)

* Updated examples in `add_p.tbl_continuous()`

* Improving error messaging

R/add_p.R

@@ -269,7 +269,7 @@ calculate_and_add_test_results <- function(x, include, group = NULL, test.args,
         if (!is.null(lst_captured_results[["result"]])) return(lst_captured_results[["result"]]) # styler: off
         # otherwise, construct a {cards}-like object with error
         dplyr::tibble(
-          group1 = x$inputs$by,
+          group1 = switch(!is_empty(x$inputs$by), x$inputs$by),
           variable = variable,
           stat_name = switch(calling_fun,
                              "add_p" = "p.value",

R/add_p.tbl_continuous.R

@@ -11,10 +11,16 @@
 #' @export
 #' @return 'tbl_continuous' object
 #'
-#' @examplesIf gtsummary:::is_pkg_installed("cardx")
+#' @examplesIf (identical(Sys.getenv("NOT_CRAN"), "true") || identical(Sys.getenv("IN_PKGDOWN"), "true")) && gtsummary:::is_pkg_installed("cardx")
+#' # Example 1 ----------------------------------
 #' trial |>
 #'   tbl_continuous(variable = age, by = trt, include = grade) |>
-#'   add_p()
+#'   add_p(pvalue_fun = label_style_pvalue(digits = 2))
+#'
+#' # Example 2 ----------------------------------
+#' trial |>
+#'   tbl_continuous(variable = age, include = grade) |>
+#'   add_p(test = everything() ~ "kruskal.test")
 add_p.tbl_continuous <- function(x,
                                  test = NULL,
                                  pvalue_fun = label_style_pvalue(digits = 1),

tests/testthat/test-add_p.tbl_continuous.R

@@ -111,3 +111,11 @@ test_that("add_p.tbl_continuous(group) works", {
     unlist(compare)
   )
 })
+
+test_that("add_p.tbl_continuous() messaging", {
+  expect_message(
+    tbl_continuous(trial, variable = age, include = grade) |>
+      add_p(test = ~"lme4"),
+    "*argument cannot be missing*"
+  )
+})