Allow specifying the limit of Coord in the opposite order to the Scale (#3958)

* Add a failing test

* Sort the limits in ascending order

Author: yutannihilation

R/scale-view.r

@@ -16,7 +16,9 @@ view_scale_primary <- function(scale, limits = scale$get_limits(),
                                continuous_range = scale$dimension(limits = limits)) {
 
   if(!scale$is_discrete()) {
-    breaks <- scale$get_breaks(continuous_range)
+    # continuous_range can be specified in arbitrary order, but
+    # continuous scales expect the one in ascending order.
+    breaks <- scale$get_breaks(sort(continuous_range))
     minor_breaks <- scale$get_breaks_minor(b = breaks, limits = continuous_range)
   } else {
     breaks <- scale$get_breaks(limits)

tests/testthat/test-scales-breaks-labels.r

@@ -264,7 +264,12 @@ test_that("equal length breaks and labels can be passed to ViewScales with limit
 
   test_view_scale <- view_scale_primary(test_scale)
   expect_identical(test_view_scale$get_breaks(), c(NA, 20, NA))
-  expect_identical(test_scale$get_labels(), c(c("0", "20", "40")))
+  expect_identical(test_view_scale$get_labels(), c(c("0", "20", "40")))
+
+  # ViewScale accepts the limits in the opposite order (#3952)
+  test_view_scale_rev <- view_scale_primary(test_scale, limits = rev(test_scale$get_limits()))
+  expect_identical(test_view_scale_rev$get_breaks(), c(NA, 20, NA))
+  expect_identical(test_view_scale_rev$get_labels(), c(c("0", "20", "40")))
 })
 
 # Visual tests ------------------------------------------------------------