Add tests for date(time) break calculation

Author: teunbrand

tests/testthat/test-scale-binned.R

@@ -4,3 +4,39 @@ test_that("binned scales only support continuous data", {
   p <- ggplot(mtcars) + geom_point(aes(disp, mpg, colour = as.character(gear))) + scale_color_binned()
   expect_snapshot_error(ggplot_build(p))
 })
+
+test_that('binned scales can calculate breaks on dates', {
+
+  data <- seq(as.Date("2000-01-01"), as.Date("2020-01-01"), length.out = 100)
+
+  scale <- scale_x_binned(trans = "date")
+  scale$train(scale$transform(data))
+  breaks <- scale$trans$inverse(scale$get_breaks())
+
+  expect_s3_class(breaks, "Date")
+  expect_equal(
+    unname(breaks),
+    as.Date(paste0(seq(2002, 2018, by = 2), "-01-01"))
+  )
+})
+
+test_that('binned scales can calculate breaks on date-times', {
+  data <- seq(
+    strptime("2000-01-01", "%Y-%m-%d"),
+    strptime("2020-01-01", "%Y-%m-%d"),
+    length.out = 100
+  )
+
+  scale <- scale_x_binned(trans = "time")
+  scale$train(scale$transform(data))
+  breaks <- scale$trans$inverse(scale$get_breaks())
+
+  expect_s3_class(breaks, "POSIXct")
+  expect_equal(
+    unname(unclass(breaks)),
+    unclass(as.POSIXct(strptime(
+      paste0(seq(2002, 2018, by = 2), "-01-01"),
+      "%Y-%m-%d"
+    )))
+  )
+})