included custom warning messages if data and/or mapping is supplied

Author: thiyangt

R/stat-function.r

@@ -84,13 +84,12 @@ stat_function <- function(mapping = NULL, data = NULL,
 
   # Warn if supplied mapping and/or data is going to be overwritten
   if (!is.null(mapping)) {
-    warn_overwritten_args("stat_function()", "mapping", "group")
+    warning("`mapping` is not used by stat_function()", call. = FALSE)
   }
   if (!is.null(data)) {
-    warn_overwritten_args("stat_function()", "data", "group")
+    warning("`data` is not used by stat_function()", call. = FALSE)
   }
 
-
 }
 
 #' @rdname ggplot2-ggproto

tests/testthat/test-stats-function.r

@@ -47,3 +47,15 @@ test_that("works with formula syntax", {
   expect_equal(ret$x, s)
   expect_equal(ret$y, s^2)
 })
+
+test_that("can control whether to preserve total or individual width", {
+  df <- data_frame(x = c("a", "b", "b"), y = c("a", "a", "b"))
+
+  p_total <- ggplot(df, aes(x, fill = y)) +
+    geom_bar(position = position_dodge(preserve = "total"), width = 1)
+  p_single <- ggplot(df, aes(x, fill = y)) +
+    geom_bar(position = position_dodge(preserve = "single"), width = 1)
+
+  expect_equal(layer_data(p_total)$x, c(1, 2.25, 1.75))
+  expect_equal(layer_data(p_single)$x, c(0.75, 2.25, 1.75))
+})