Report a helpful error if linters_with_tags() specifies no tags. (#2942)

Author: mcol

R/with.R

@@ -92,6 +92,9 @@ modify_defaults <- function(defaults, ...) {
 #' }
 #' @export
 linters_with_tags <- function(tags, ..., packages = "lintr", exclude_tags = "deprecated") {
+  if (missing(tags)) {
+    cli_abort("{.arg tags} was not specified. Available tags: {available_tags()}")
+  }
   if (!is.character(tags) && !is.null(tags)) {
     cli_abort("{.arg tags} must be a character vector, or {.code NULL}, not {.obj_type_friendly {tags}}.")
   }

tests/testthat/test-linter_tags.R

@@ -41,6 +41,7 @@ test_that("default_linters and default tag match up", {
 test_that("warnings occur only for deprecated linters", {
   skip_if_not_installed("cyclocomp") # actually we expect a warning there
 
+  expect_error(linters_with_tags(), "`tags` was not specified. Available tags:")
   expect_silent(linters_with_tags(tags = NULL))
   num_deprecated_linters <- nrow(available_linters(tags = "deprecated", exclude_tags = NULL))
   outer_env <- new.env(parent = emptyenv())