Error on empty character vector args in undesirable linters

Closes #1867

Author: IndrajeetPatil

R/undesirable_function_linter.R

@@ -58,6 +58,9 @@
 undesirable_function_linter <- function(fun = default_undesirable_functions,
                                         symbol_is_undesirable = TRUE) {
   stopifnot(is.logical(symbol_is_undesirable))
+  if (is.null(names(fun)) || !all(nzchar(names(fun))) || length(fun) == 0L) {
+    stop("'fun' should be a non-empty named character vector; use missing elements to indicate default messages.")
+  }
 
   xp_condition <- xp_and(
     xp_text_in_table(names(fun)),

R/undesirable_operator_linter.R

@@ -43,8 +43,8 @@
 #' @seealso [linters] for a complete list of linters available in lintr.
 #' @export
 undesirable_operator_linter <- function(op = default_undesirable_operators) {
-  if (is.null(names(op)) || !all(nzchar(names(op)))) {
-    stop("'op' should be a named character vector; use missing elements to indicate default messages.")
+  if (is.null(names(op)) || !all(nzchar(names(op))) || length(op) == 0L) {
+    stop("'op' should be a non-empty named character vector; use missing elements to indicate default messages.")
   }
   undesirable_operator_metadata <- merge(
     # infix must be handled individually below; non-assignment `=` are always OK

tests/testthat/test-undesirable_function_linter.R

@@ -52,3 +52,30 @@ test_that("Line numbers are extracted correctly", {
   lines <- c(rep(letters, 10L), "tmp <- tempdir()")
   expect_lint(paste(lines, collapse = "\n"), "undesirable", undesirable_function_linter(c(tempdir = NA)))
 })
+
+test_that("invalid inputs fail correctly", {
+  error_msg <- "'fun' should be a non-empty named character vector"
+
+  expect_error(
+    undesirable_function_linter("***"),
+    error_msg,
+    fixed = TRUE
+  )
+  expect_error(
+    undesirable_function_linter(c("***" = NA, NA)),
+    error_msg,
+    fixed = TRUE
+  )
+  expect_error(
+    undesirable_function_linter(fun = NULL),
+    error_msg,
+    fixed = TRUE
+  )
+
+  expect_error(
+    undesirable_function_linter(symbol_is_undesirable = 1.0),
+    "is.logical(symbol_is_undesirable) is not TRUE",
+    fixed = TRUE
+  )
+})
+

tests/testthat/test-undesirable_operator_linter.R

@@ -51,16 +51,24 @@ test_that("undesirable_operator_linter vectorizes messages", {
 })
 
 test_that("invalid inputs fail correctly", {
+  error_msg <- "'op' should be a non-empty named character vector"
+
   expect_error(
     undesirable_operator_linter("***"),
-    "'op' should be a named character vector",
+    error_msg,
     fixed = TRUE
   )
   expect_error(
     undesirable_operator_linter(c("***" = NA, NA)),
-    "'op' should be a named character vector",
+    error_msg,
     fixed = TRUE
   )
+  expect_error(
+    undesirable_operator_linter(op = NULL),
+    error_msg,
+    fixed = TRUE
+  )
+
   expect_error(
     undesirable_operator_linter(c("***" = NA)),
     "Did not recognize any valid operators in request for: ***",