Add tests for binned breaks and limits

Author: teunbrand

tests/testthat/test-scale-binned.R

@@ -4,3 +4,42 @@ 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 limits can expand to fit breaks", {
+  # See also #5095
+
+  scale <- scale_x_binned(right = FALSE, show.limits = TRUE)
+  scale$train(c(14, 29))
+
+  limits <- scale$get_limits()
+  breaks <- scale$get_breaks()
+  new_limits <- scale$get_limits()
+
+  # Positive control
+  expect_equal(limits,     c(14, 29))
+  # Test case, should have been updated in break calculation
+  expect_equal(new_limits, c(14, 30))
+
+  # Negative control
+  # Now, new limits should not be updated because limits were given instead
+  # of computed
+  scale <- scale_x_binned(right = FALSE, show.limits = TRUE,
+                          limits = c(14, 29))
+  limits <- scale$get_limits()
+  breaks <- scale$get_breaks()
+  new_limits <- scale$get_limits()
+
+  expect_equal(limits, new_limits)
+})
+
+test_that("binned limits should not compute out-of-bounds breaks", {
+  scale <- scale_x_binned(n.breaks = 10)
+  scale$train(c(1, 9))
+
+  limits <- scale$get_limits()
+  breaks <- scale$get_breaks()
+  expect_length(breaks, 7) # Not the requested 10 due to oob discarding
+  expect_true(all(
+    breaks > limits[1] & breaks < limits[2]
+  ))
+})