Move theme generation helpers into package and add tests

R/theme_settings.R

   table_row_border_color          = solarized$base00,
   table_row_even_background_color = solarized$base02
 )
+
+
+# Theme Generating Helpers ----------------------------------------------
+
+
+plural_element <- function(css_name) {
+  is_mult <- grepl(",|and|or", css_name)
+  is_class <- grepl("^\\.", css_name)
+  ifelse(is_class,
+         ifelse(is_mult, "classes", "class"),
+         ifelse(is_mult, "elements", "element")
+  )
+}
+
+element_description <- function(element) {
+  out <- rep("", length(element))
+  multiple <- grepl("multiple", element)
+  out[multiple] <- "Modifies multiple CSS classes or elements."
+
+  ifelse(
+    multiple | is.na(element) | element == "",
+    out,
+    glue::glue("Modifies the `{element}` {plural_element(element)}.")
+  )

inst/scripts/generate_theme_functions.R

 source(here::here("R/theme_settings.R"))
-
-plural_element <- function(css_name) {
-  is_mult <- grepl(",|and|or", css_name)
-  is_class <- grepl("^\\.", css_name)
-  ifelse(is_class,
-    ifelse(is_mult, "classes", "class"),
-    ifelse(is_mult, "elements", "element")
-  )
-}
-
-element_description <- function(element) {
-  ifelse(
-    grepl("multiple", element),
-    "Modifies multiple CSS classes or elements.",
-    glue::glue("Modifies the `{element}` {plural_element(element)}.")
-    )
-}
+# R/theme_settings.R contains element_description() and plural_elements()
 
 setup_theme_function <- function(
   f_name = "write_xaringan_theme",

tests/testthat/test-helpers.R

+context("test-helpers")
+
+test_that("element_description", {
+  text_in <- c("multiple", NA, "", ".remark-slide-content", "h1", "pre, code")
+  text_out <- c(
+    "Modifies multiple CSS classes or elements.",
+    "",
+    "",
+    "Modifies the `.remark-slide-content` class.",
+    "Modifies the `h1` element.",
+    "Modifies the `pre, code` elements."
+  )
+  expect_equal(element_description(text_in), text_out)
+})