test_that("vennItem works for 2 sets", {
  sets <- list(A = c("apple","banana"), B = c("banana","kiwi"))
  p <- vennItem(sets)
  expect_s3_class(p, "ggplot")
})

test_that("vennItem works for 3 sets", {
  sets <- list(A = c("apple","banana"), B = c("banana","kiwi"), C = c("banana","kiwi","apple","pear"))
  p <- vennItem(sets)
  expect_s3_class(p, "ggplot")
})