test_that("isocubeGrob() works", {
    skip_if_not(getRversion() >= "4.3.0")
    skip_if_not(isTRUE(capabilities("cairo")))
    f <- tempfile(fileext = ".png")
    png(f, type = "cairo")
    gp_text <- grid::gpar(fontsize = 72)
    grid.isocube(top = grid::textGrob("top", gp = gp_text), 
                 right = grid::textGrob("right", gp = gp_text),
                 left = grid::textGrob("left", gp = gp_text))
    dev.off()
    expect_true(file.size(f) > 0)
    unlink(f)
})