Fix colourbar's ticks.length argument not working (#5529)

* Fix `ticks.length` not working

* include tick length in test

Author: teunbrand

R/guide-colorbar.R

@@ -429,14 +429,11 @@ GuideColourbar <- ggproto(
       "horizontal" = c("bottom", "top"),
       "vertical"   = c("right", "left")
     )
-    elements$ticks_length <- rep(elements$ticks_length, length.out = 2)
-    elem1 <- elem2 <- elements
-    elem1$ticks_length <- elements$ticks_length[2]
-    elem2$ticks_length <- elements$ticks_length[1]
+    ticks_length <- rep(elements$ticks_length, length.out = 2)
 
     grobTree(
-      Guide$build_ticks(pos, elem1, params, position[1]),
-      Guide$build_ticks(pos, elem2, params, position[2])
+      Guide$build_ticks(pos, elements, params, position[1], ticks_length[1]),
+      Guide$build_ticks(pos, elements, params, position[2], ticks_length[2])
     )
   },
 

tests/testthat/_snaps/guides/white-to-red-colorbar-thick-black-ticks-green-frame.svg renamed to tests/testthat/_snaps/guides/white-to-red-colorbar-long-thick-black-ticks-green-frame.svg

@@ -811,14 +811,15 @@ test_that("colorbar can be styled", {
     p + scale_color_gradient(low = 'white', high = 'red')
   )
 
-  expect_doppelganger("white-to-red colorbar, thick black ticks, green frame",
+  expect_doppelganger("white-to-red colorbar, long thick black ticks, green frame",
     p + scale_color_gradient(
           low = 'white', high = 'red',
           guide = guide_colorbar(
             frame = element_rect(colour = "green"),
             frame.linewidth = 1.5 / .pt,
             ticks.colour = "black",
-            ticks.linewidth = 2.5 / .pt
+            ticks.linewidth = 2.5 / .pt,
+            ticks.length = unit(0.4, "npc")
             )
         )
     )