spread() works fine when the id variable has names.

closes tidyverse#525

NEWS.md

@@ -10,6 +10,8 @@
 
 * `crossing()` preserves factor levels (#410).
 
+* `spread()` works when the id variable has names (#525).
+
 # tidyr 0.8.2
 
 * `separate()` now accepts `NA` as a column name in the `into` argument to

R/id.R

@@ -38,7 +38,7 @@ id <- function(.variables, drop = FALSE) {
 }
 
 id_var <- function(x, drop = FALSE) {
-  if (!is_null(attr(x, "n")) && !drop) return(x)
+  if (!is_null(attr(x, "n", exact = TRUE)) && !drop) return(x)
 
   if (is.factor(x) && !drop) {
     x_na <- addNA(x, ifany = TRUE)

tests/testthat/test-id.R

@@ -1,7 +1,7 @@
 context("id")
 
 test_that("drop preserves count of factor levels", {
-  x <- factor(, levels = c("a", "b"))
+  x <- factor(levels = c("a", "b"))
   expect_equal(id_var(x), structure(integer(), n = 2))
   expect_equal(id(data.frame(x)), structure(integer(), n = 2))
 })
@@ -10,3 +10,8 @@ test_that("id works with dimensions beyond integer range", {
   df <- data.frame(matrix(c(1, 2), nrow = 2, ncol = 32))
   expect_equal(id(df), structure(c(1, 2), n = 2 ^ 32))
 })
+
+test_that("id_var() handles named vectors (#525)", {
+  res <- id_var(c(a = 5, b = 3, c = 5))
+  expect_equal(res, structure(c(2L, 1L, 2L), n = 2L))
+})

tests/testthat/test-spread.R

@@ -278,3 +278,14 @@ test_that("ulevels returns unique elements of a list for a list input", {
   test_list <- list(a = 1:6, b = 1:6)
   expect_equal(ulevels(test_list), unique(test_list))
 })
+
+test_that("spread works when id column has names (#525)", {
+  df <- tibble(
+    key = factor(c("a", "b", "c"), levels = letters[1:5]),
+    out = 1:3,
+    id  = c(a = 1, b = 2, c = 3)
+  )
+  res <- spread(df, key, out, drop = FALSE)
+  expect_equal(names(res), c("id", letters[1:5]))
+})
+