Fix tidyverse#3014 force col_names (tidyverse#3015)

* Fix tidyverse#3014 force col_names to make sure it is calculated before x is converted to a list

* Add unit test

Author: thomasp85

R/performance.R

@@ -27,6 +27,7 @@ data.frame <- function(...) {
 }
 
 mat_2_df <- function(x, col_names = colnames(x), .check = FALSE) {
+  force(col_names)
   x <- lapply(seq_len(ncol(x)), function(i) x[, i])
   if (!is.null(col_names)) names(x) <- col_names
   new_data_frame(x)

tests/testthat/test-stat-ellipsis.R

@@ -0,0 +1,12 @@
+context("stat_ellipsis")
+
+test_that("stat_ellipsis returns correct data format", {
+  n_seg <- 40
+  d <- data_frame(x = c(1, 1, 4, 4, 4, 3, 3, 1), y = c(1:4, 1:4), id = rep(1:2, each = 4))
+  p <- ggplot(d, aes(x = x, y = y, group = id)) +
+    geom_point() +
+    stat_ellipse(segments = n_seg)
+  out <- layer_data(p, 2)
+  expect_equal(nrow(out), (n_seg + 1) * 2)
+  expect_equal(unique(out$group), c(1, 2))
+})