fix duplicate line_length lints. (#682)

* fix duplicate line_length lints.

fixes #681

also added a regression test.

* update NEWS.md

* incorporate suggestions

NEWS.md

@@ -31,6 +31,7 @@
 * Lints are now marked with the name of the `linter` that caused them instead of the name of their implementation
   function (#664, #673, @AshesITR).
 * Fixed `spaces_left_parentheses_linter` sporadically causing warnings (#654, #674, @AshesITR)
+* Fixed `line_length_linter` causing duplicate lints for lines containing multiple expressions (#681, #682, @AshesITR)
 
 # lintr 2.0.1
 

R/line_length_linter.R

@@ -4,10 +4,16 @@
 line_length_linter <- function(length) {
   function(source_file) {
 
-    lapply(names(source_file$lines)[vapply(source_file$lines, nchar, integer(1)) > length],
+    # Only go over complete file
+    if (is.null(source_file$file_lines)) return(list())
+
+    oversized_lines <- which(vapply(source_file$file_lines, nchar, integer(1)) > length)
+
+    lapply(oversized_lines,
       function(line_number) {
+
         col_start <- 1
-        line <- source_file$lines[as.character(line_number)]
+        line <- source_file$file_lines[line_number]
         col_end <- unname(nchar(line))
 
         Lint(

tests/testthat/test-line_length_linter.R

@@ -1,4 +1,3 @@
-context("line_length_linter")
 test_that("returns the correct linting", {
 
   expect_lint("blah",
@@ -30,4 +29,14 @@ test_that("returns the correct linting", {
   expect_lint("aaaaaaaaaaaaaaaaaaaab",
     rex("Lines should not be more than 20 characters"),
     line_length_linter(20))
+
+  # Don't duplicate lints
+  expect_length(
+    lint(
+      "x <- 2 # ------------\n",
+      linters = line_length_linter(20),
+      parse_settings = FALSE
+    ),
+    1L
+  )
 })