Add examples for unnecessary_lambda_linter() (#1888)

* Add examples for `unnecessary_lambda_linter()`

* remove brace lints

* Empty commit to trigger CI

* more OK examples

Author: IndrajeetPatil

R/unnecessary_lambda_linter.R

@@ -4,6 +4,29 @@
 #'   e.g. `lapply(DF, sum)` is the same as `lapply(DF, function(x) sum(x))` and
 #'   the former is more readable.
 #'
+#' @examples
+#' # will produce lints
+#' lint(
+#'   text = "lapply(list(1:3, 2:4), function(xi) sum(xi))",
+#'   linters = unnecessary_lambda_linter()
+#' )
+#'
+#' # okay
+#' lint(
+#'   text = "lapply(list(1:3, 2:4), sum)",
+#'   linters = unnecessary_lambda_linter()
+#' )
+#'
+#' lint(
+#'   text = 'lapply(x, function(xi) grep("ptn", xi))',
+#'   linters = unnecessary_lambda_linter()
+#' )
+#'
+#' lint(
+#'   text = "lapply(x, function(xi) data.frame(col = xi))",
+#'   linters = unnecessary_lambda_linter()
+#' )
+#'
 #' @evalRd rd_tags("unnecessary_lambda_linter")
 #' @seealso [linters] for a complete list of linters available in lintr.
 #' @export

man/unnecessary_lambda_linter.Rd

@@ -64,36 +64,38 @@ test_that("unnecessary_lambda_linter doesn't apply to keyword args", {
 })
 
 test_that("purrr-style anonymous functions are also caught", {
+  linter <- unnecessary_lambda_linter()
+
   # TODO(michaelchirico): this is just purrr::flatten(x). We should write another
   #   linter to encourage that usage.
-  expect_lint("purrr::map(x, ~.x)", NULL, unnecessary_lambda_linter())
-  expect_lint("purrr::map_df(x, ~lm(y, .x))", NULL, unnecessary_lambda_linter())
-  expect_lint("map_dbl(x, ~foo(bar = .x))", NULL, unnecessary_lambda_linter())
+  expect_lint("purrr::map(x, ~.x)", NULL, linter)
+  expect_lint("purrr::map_df(x, ~lm(y, .x))", NULL, linter)
+  expect_lint("map_dbl(x, ~foo(bar = .x))", NULL, linter)
 
   expect_lint(
     "purrr::map(x, ~foo(.x))",
     rex::rex("Pass foo directly as a symbol to map()"),
-    unnecessary_lambda_linter()
+    linter
   )
   expect_lint(
     "purrr::map_int(x, ~foo(.x, y))",
     rex::rex("Pass foo directly as a symbol to map_int()"),
-    unnecessary_lambda_linter()
+    linter
   )
   expect_lint(
     "purrr::map_vec(x, ~foo(.x, y))",
     rex::rex("Pass foo directly as a symbol to map_vec()"),
-    unnecessary_lambda_linter()
+    linter
   )
 })
 
 test_that("cases with braces are caught", {
   linter <- unnecessary_lambda_linter()
-  print_msg <- rex::rex("Pass print directly as a symbol to lapply()")
+  lint_msg <- rex::rex("Pass print directly as a symbol to lapply()")
 
   expect_lint(
     "lapply(x, function(xi) { print(xi) })",
-    print_msg,
+    lint_msg,
     linter
   )
 
@@ -103,7 +105,7 @@ test_that("cases with braces are caught", {
         print(xi)
       })
     "),
-    print_msg,
+    lint_msg,
     linter
   )