tests/testthat/test_get_panel.R

In cowplot: Streamlined Plot Theme and Plot Annotations for 'ggplot2'

context("get_panel")

test_that("get panel", {
  df <- data.frame(x = 1:3, y = 1:3, z = factor(c("a", "b", "c")))
  p <- ggplot(df, aes(x, y)) + geom_point()

  panel <- get_panel(p)

  expect_s3_class(panel, "gTree")
  expect_match(panel$name, "^panel-1\\.gTree\\.")

  # get_panel() returns just 1 unless specified
  facet_p <- p + facet_wrap(~z)
  expect_warning(get_panel(facet_p))
  expect_type(get_panel(facet_p, return_all = TRUE), "list")
})