add test

tests/testthat/_snaps/utilities.md

@@ -54,3 +54,19 @@
 
     Can't recycle `..1` (size 4) to match `..2` (size 0).
 
+# summary method gives a nice summary
+
+    Code
+      summary(p)
+    Output
+      data: manufacturer, model, displ, year, cyl, trans, drv, cty, hwy, fl,
+        class [234x11]
+      mapping:  x = ~displ, y = ~hwy, colour = ~drv
+      scales:   x, xmin, xmax, xend, xintercept, xmin_final, xmax_final, xlower, xmiddle, xupper, x0, colour 
+      faceting:  ~year, ~cyl 
+      -----------------------------------
+      geom_point: na.rm = FALSE
+      stat_identity: na.rm = FALSE
+      position_identity 
+      
+

tests/testthat/test-utilities.R

@@ -196,3 +196,16 @@ test_that("expose/ignore_data() can round-trip a data.frame", {
   expect_equal(test, df[, c("a", "c", "b", "d")])
 
 })
+
+test_that("summary method gives a nice summary", {
+  # This test isn't important enough to break anything on CRAN
+  skip_on_cran()
+
+  p <- ggplot(mpg, aes(displ, hwy, colour = drv)) +
+    geom_point() +
+    scale_x_continuous() +
+    scale_colour_brewer() +
+    facet_grid(year ~ cyl)
+
+  expect_snapshot(summary(p))
+})