testdata <- data.frame( # NA block and pattern block
  var_a = c(NA, 2, 3, 1,NA,NA, 5,2,1,4,1,3),
  var_b = c(NA,NA, 4,NA, 2,NA,NA,5,4,3,1,3),
  var_c = c(NA,NA,NA, 5,NA, 3,NA,3,5,2,1,4))

testdata_kim_et_al <- data.frame(
  var_1 = c(5,5),
  var_2 = c(5,5),
  var_3 = c(5,5),
  var_4 = c(5,1))

test_that("resp_nondif output test Kim et al. 2017",{
  expect_equal(round(mean(resp_nondifferentiation(testdata_kim_et_al)$simple_nondifferentiation),2),0.5)
  expect_equal(round(mean(resp_nondifferentiation(testdata_kim_et_al)$mean_root_pairs),2),0.5)
  expect_equal(round(mean(resp_nondifferentiation(testdata_kim_et_al)$max_identical_rating),2),0.88)
  expect_equal(round(mean(resp_nondifferentiation(testdata_kim_et_al)$scale_point_variation),2),0.19)
  # Extra tests for id input
  expect_error(resp_nondifferentiation(x = testdata,
                                  id = 0),
               regexp = "id is not of type logical with length one or a numeric or character vector with length equal to the number of rows of x.")
  expect_error(resp_nondifferentiation(x = testdata,
                                  id = c(T,T)),
               regexp = "id is not of type numeric or character")
  expect_error(resp_nondifferentiation(x = testdata,
                                  id = c(1,2)),
               regexp = "Supply an `id` variable with the same number of elements as there are rows in x.")
  expect_error(resp_nondifferentiation(x = testdata,
                                  id = c(1:11,11)),
               regexp = "Supply an `id` variable which uniquely identifies each respondent by position.")
  })