Add test to check that ggplotly does not break discrete x-axis in facet panels with only one category.

Author: trekonom

tests/testthat/test-facet-axis.R

@@ -0,0 +1,11 @@
+test_that("ggplotly does not break discrete x-axis with facet_yyyy in panels > 1 with only one category", {
+  d <- data.frame(cat = c("A", "A", "A"), pan = paste("Panel", c(1, 2, 2)))
+  gp <- ggplot(d, aes(cat)) +
+    geom_bar() +
+    facet_wrap(~pan)
+  L <- plotly_build(ggplotly(gp))
+  # tickvals, ticktext and categoryarray have class 'AsIs'
+  expect_equal(class(L$x$layout$xaxis2$tickvals), "AsIs")
+  expect_equal(class(L$x$layout$xaxis2$ticktext), "AsIs")
+  expect_equal(class(L$x$layout$xaxis2$categoryarray), "AsIs")
+})