Return NULL if the mapping is NULL

Author: yutannihilation

R/aes-calculated.r

@@ -87,7 +87,11 @@ strip_dots <- function(expr) {
 # Convert aesthetic mapping into text labels
 make_labels <- function(mapping) {
   default_label <- function(aesthetic, mapping) {
-    # e.g., geom_smooth(aes(colour = "loess")) or aes(y = NULL)
+    if (is.null(mapping)) {
+      return(NULL)
+    }
+
+    # e.g., geom_smooth(aes(colour = "loess"))
     if (is.atomic(mapping)) {
       return(aesthetic)
     }

tests/testthat/test-aes-calculated.r

@@ -34,7 +34,8 @@ test_that("make_labels() deprases mappings properly", {
   # long expression is abbreviated with ...
   expect_identical(make_labels(aes(x = 2 * x * exp(`coef 1` * x^2) * 2 * x * exp(`coef 1` * x^2) * 2 * x)),
                    list(x = "2 * x * exp(`coef 1` * x^2) * 2 * x * exp(`coef 1` * x^2) * 2 * ..."))
-  # if the mapping is a literal or NULL, the aesthetics is used
+  # if the mapping is a literal, the aesthetics is used
   expect_identical(make_labels(aes(x = 1)), list(x = "x"))
-  expect_identical(make_labels(aes(x = NULL)), list(x = "x"))
+  # if the mapping is NULL, there will be no labels
+  expect_identical(make_labels(aes(x = NULL)), list(x = NULL))
 })