Remove missing data in StatBoxplot (#2629)

Fixes #2615. Closes #2616

Author: karawoo

R/stat-boxplot.r

@@ -46,6 +46,12 @@ StatBoxplot <- ggproto("StatBoxplot", Stat,
   non_missing_aes = "weight",
   setup_data = function(data, params) {
     data$x <- data$x %||% 0
+    data <- remove_missing(
+      data,
+      na.rm = FALSE,
+      vars = "x",
+      name = "stat_boxplot"
+    )
     data
   },
 

tests/testthat/test-stat-boxplot.R

@@ -0,0 +1,22 @@
+context("stat_boxplot")
+
+test_that("stat_boxplot drops missing rows with a warning", {
+
+  p1 <- ggplot(PlantGrowth, aes(x = group, y = weight)) +
+    geom_boxplot(position = "dodge") +
+    scale_x_discrete(limits = c("trt1", "ctrl"))
+
+  p2 <- ggplot(PlantGrowth, aes(x = group, y = weight)) +
+    geom_boxplot(position = "dodge2") +
+    scale_x_discrete(limits = c("trt1", "ctrl"))
+
+  expect_warning(
+    ggplot_build(p1),
+    "Removed 10 rows containing missing values \\(stat_boxplot\\)\\."
+  )
+  expect_warning(
+    ggplot_build(p2),
+    "Removed 10 rows containing missing values \\(stat_boxplot\\)\\."
+  )
+
+})