test_that("checking the visibility of Excel worksheets", {
  # Create workbooks
  wb.xls <- loadWorkbook("resources/testWorkbookHiddenSheets.xls", create = FALSE)
  wb.xlsx <- loadWorkbook("resources/testWorkbookHiddenSheets.xlsx", create = FALSE)

  # Check if sheets are visible (*.xls)
  expect_false(isSheetVisible(wb.xls, 2))
  expect_false(isSheetVisible(wb.xls, "BBB"))
  expect_true(isSheetVisible(wb.xls, 1))
  expect_true(isSheetVisible(wb.xls, "AAA"))
  expect_true(isSheetVisible(wb.xls, 3))
  expect_true(isSheetVisible(wb.xls, "CCC"))
  expect_false(isSheetVisible(wb.xls, 4))
  expect_false(isSheetVisible(wb.xls, "DDD"))

  # Check if sheets are visible (*.xlsx)
  expect_false(isSheetVisible(wb.xlsx, 2))
  expect_false(isSheetVisible(wb.xlsx, "BBB"))
  expect_true(isSheetVisible(wb.xlsx, 1))
  expect_true(isSheetVisible(wb.xlsx, "AAA"))
  expect_true(isSheetVisible(wb.xlsx, 3))
  expect_true(isSheetVisible(wb.xlsx, "CCC"))
  expect_false(isSheetVisible(wb.xlsx, 4))
  expect_false(isSheetVisible(wb.xlsx, "DDD"))
})