test_df <- data.frame(x = c(NA,2,3),
                      y = c(1,NA,3),
                      z = c(1,2,3))

test_that("label_miss_2d errors on the first NULL entry",{
  expect_snapshot(
    error = TRUE,
    label_miss_2d(NULL, 3)
    )
})

test_that("label_miss_2d errors on the second NULL entry",{
  expect_snapshot(
    error = TRUE,
    label_miss_2d(3, NULL)
    )
})

test_that("label_miss_2d errors when both are NULL",{
  expect_snapshot(
    error = TRUE,
    label_miss_2d(NULL, NULL)
    )
})

test_that("label_miss_2d returns a vector of the same length as the input", {
  expect_length(
    label_miss_2d(test_df$x, test_df$y),
    nrow(test_df)
  )
})

test_that("label_miss_2d returns factor vector",{
  expect_type(label_miss_2d(test_df$x, test_df$y),
              # typeof(factor()) is "integer"
              "integer")
})


test_that("label_miss_2d identifies the correct location of missingness",{
  expect_snapshot(
    label_miss_2d(test_df$x, test_df$y)
  )
  expect_snapshot(
    label_miss_2d(test_df$y, test_df$z)
  )
  expect_snapshot(
    label_miss_2d(test_df$x, test_df$z)
               )
})