Error earlier for missing lint_message (#2541)

* Error earlier for missing lint_message

* include PR#

Author: MichaelChirico

NEWS.md

@@ -49,6 +49,7 @@
 * `todo_comment_linter()` has a new argument `except_regex` for setting _valid_ TODO comments, e.g. for forcing TODO comments to be linked to GitHub issues like `TODO(#154)` (#2047, @MichaelChirico).
 * `vector_logic_linter()` is extended to recognize incorrect usage of scalar operators `&&` and `||` inside subsetting expressions like `dplyr::filter(x, A && B)` (#2166, @MichaelChirico).
 * `any_is_na_linter()` is extended to catch the unusual usage `NA %in% x` (#2113, @MichaelChirico).
+* `make_linter_from_xpath()` errors up front when `lint_message` is missing (instead of delaying this error until the linter is used, #2541, @MichaelChirico).
 
 ### New linters
 

R/make_linter_from_xpath.R

@@ -19,7 +19,8 @@ make_linter_from_xpath <- function(xpath,
   level <- match.arg(level)
 
   stopifnot(
-    "xpath should be a character string" = is.character(xpath) && length(xpath) == 1L && !is.na(xpath)
+    "xpath should be a character string" = is.character(xpath) && length(xpath) == 1L && !is.na(xpath),
+    "lint_message is required" = !missing(lint_message)
   )
 
   xml_key <- if (level == "expression") "xml_parsed_content" else "full_xml_parsed_content"
@@ -55,7 +56,8 @@ make_linter_from_function_xpath <- function(function_names,
 
   stopifnot(
     "function_names should be a character vector" = is.character(function_names) && length(function_names) > 0L,
-    "xpath should be a character string" = is.character(xpath) && length(xpath) == 1L && !is.na(xpath)
+    "xpath should be a character string" = is.character(xpath) && length(xpath) == 1L && !is.na(xpath),
+    "lint_message is required" = !missing(lint_message)
   )
 
   function() {

tests/testthat/test-make_linter_from_xpath.R

@@ -26,4 +26,7 @@ test_that("input validation works", {
   expect_error(make_linter_from_xpath(letters), err_msg, fixed = TRUE)
   expect_error(make_linter_from_xpath(NA_character_), err_msg, fixed = TRUE)
   expect_error(make_linter_from_xpath(character()), err_msg, fixed = TRUE)
+
+  err_msg <- if (getRversion() < "4.0.0") "!missing(lint_message)" else "lint_message is required"
+  expect_error(make_linter_from_xpath(""), err_msg, fixed = TRUE)
 })