Fix tidyverse#2429. Add NEWS item and test cases for value-breaks matching in scale_manual

Author: Anthony Chiu

NEWS.md

@@ -84,6 +84,12 @@
 
 * Increase the default `nbin` of `guide_colourbar()` to place the ticks more precisely (#3508, @yutannihilation).
 
+* Modified `manual_scale` to match `values` with the order of `breaks` whenever
+  `values` is an unnamed vector. Previously, unnamed `values` would be matched
+  to the limits of the scale and ignore the order of any `breaks` provided. Note
+  that this may change the appearance of plots that previously relied on the
+  unordered behaviour. (#2429, @idno0001)
+
 # ggplot2 3.2.1
 
 This is a patch release fixing a few regressions introduced in 3.2.0 as well as

tests/testthat/test-scale-manual.r

@@ -67,3 +67,17 @@ test_that("generic scale can be used in place of aesthetic-specific scales", {
 
   expect_equal(layer_data(p1), layer_data(p2))
 })
+
+test_that("named values do not match with breaks in manual scales", {
+   s <- scale_fill_manual(values = c("data_red" = "red", "data_black" = "black"),
+                          breaks = c("data_black", "data_red"))
+   s$train(c("data_black", "data_red"))
+   expect_equal(s$map(c("data_red", "data_black")), c("red", "black"))
+})
+
+test_that("unnamed values match breaks in manual scales", {
+   s <- scale_fill_manual(values = c("red", "black"),
+                          breaks = c("data_red", "data_black"))
+   s$train(c("data_red", "data_black"))
+   expect_equal(s$map(c("data_red", "data_black")), c("red", "black"))
+})