Add tests for warnings when using stat_bin with y values

inst/tests/test-stats.r

@@ -23,6 +23,28 @@ test_stat <- function(stat) {
   stat$calc_statistic(dat, NULL)
 }
 
+context("stat-bin")
+
+test_that("stat_sum", {
+  dat <- data.frame(x = c("a", "b", "c"), y = c(1, 5, 10))
+
+  # Should get a warning when mapping/setting y and also using stat_bin
+  expect_warning(p <- ggplot_build(ggplot(dat, aes(x=x, y=y)) + geom_bar()),
+    "Mapping a variable to y and also using stat=\"bin\"")
+  expect_warning(p <- ggplot_build(ggplot(dat, aes(x=x, y=y)) + geom_bar(stat="bin")),
+    "Mapping a variable to y and also using stat=\"bin\"")
+
+  expect_warning(p <- ggplot_build(ggplot(dat, aes(x=x)) + geom_bar(y=5)),
+    "Mapping a variable to y and also using stat=\"bin\"")
+
+  # This gives an error and a warning (it would probably be OK if just one
+  # of these happened, but this test looks for both)
+  dat2 <- data.frame(x = c("a", "b", "c", "a", "b", "c"), y = c(1, 5, 10, 2, 3, 4))
+  expect_warning(expect_error(
+    p <- ggplot_build(ggplot(dat2, aes(x=x, y=y)) + geom_bar())))
+})
+
+
 context("stat-sum")
 
 test_that("stat_sum", {