handle alist(kwd = ) false positive (#1643)

Co-authored-by: Indrajeet Patil <[email protected]>

Author: MichaelChirico

NEWS.md

@@ -15,6 +15,8 @@
 * `object_usage_linter()` gains `skip_with` argument to skip code in `with()` expressions.
   To be consistent with `R CMD check`, it defaults to `TRUE` (#941, #1458, @IndrajeetPatil).
 
+* `spaces_inside_linter()` allows terminal missing keyword arguments (e.g. `alist(arg = )`; #540, @MichaelChirico)
+
 ## New and improved features
 
 * New `get_r_string()` helper to get the R-equivalent value of a string, especially useful for R-4-style raw strings.

R/spaces_inside_linter.R

@@ -22,7 +22,9 @@ spaces_inside_linter <- function() {
     and @start != preceding-sibling::*[1]/@end + 1
     and @line1 = preceding-sibling::*[1]/@line2
   "
-  right_xpath <- glue::glue("//OP-RIGHT-BRACKET[{right_xpath_condition}] | //OP-RIGHT-PAREN[{right_xpath_condition}]")
+  right_xpath <- glue::glue("
+  //OP-RIGHT-BRACKET[{right_xpath_condition}]
+  | //OP-RIGHT-PAREN[{right_xpath_condition} and not(preceding-sibling::*[1][self::EQ_SUB])]")
 
   Linter(function(source_expression) {
     if (!is_lint_level(source_expression, "file")) {

tests/testthat/test-infix_spaces_linter.R

@@ -166,3 +166,14 @@ test_that("multi-line, multi-expression case is caught", {
     infix_spaces_linter()
   )
 })
+
+test_that("Rules around missing arguments are respected", {
+  linter <- infix_spaces_linter()
+  lint_msg <- rex::rex("Put spaces around all infix operators.")
+
+  expect_lint("switch(a = , b = 2)", NULL, linter)
+  expect_lint("alist(missing_arg = )", NULL, linter)
+
+  expect_lint("switch(a =, b = 2)", lint_msg, linter)
+  expect_lint("alist(missing_arg =)", lint_msg, linter)
+})

tests/testthat/test-spaces_inside_linter.R

@@ -110,3 +110,7 @@ test_that("mutli-line expressions have good markers", {
     spaces_inside_linter()
   )
 })
+
+test_that("terminal missing keyword arguments are OK", {
+  expect_lint("alist(missing_arg = )", NULL, spaces_inside_linter())
+})