test_that("miss_case_table errors when given wrong type", {
  expect_snapshot(
    error = TRUE,
    miss_case_table(NULL)
  )
  expect_snapshot(
    error = TRUE,
    miss_case_table(1)
  )
  expect_snapshot(
    error = TRUE,
    miss_case_table("a")
  )
  expect_snapshot(
    error = TRUE,
    miss_case_table(matrix(0))
  )
})

aq_group <- dplyr::group_by(airquality, Month)

test_that("miss_case_table produces a tibble", {
  expect_s3_class(miss_case_table(airquality), "tbl_df")
  expect_s3_class(miss_case_table(aq_group), "tbl_df")
})

test_that("grouped_df returns 1 more column than regular miss_case_table", {
  expect_equal(
    ncol(miss_case_table(aq_group)),
    ncol(miss_case_table(airquality)) + 1
  )
})

test_that("grouped_df returns a column named 'Month'", {
  expect_identical(
    names(miss_case_table(aq_group)),
    c("Month", "n_miss_in_case", "n_cases", "pct_cases")
  )
})

test_that("grouped_df returns a dataframe with more rows than regular", {
  expect_gt(
    nrow(miss_case_table(aq_group)),
    nrow(miss_case_table(airquality))
  )
})

test_that("grouped_df returns a column named 'Month' with the right levels", {
  expect_identical(
    unique(miss_case_table(aq_group)$Month),
    5:9
  )
})