test_that("properties of permutations are as expected", {
  set.seed(2000)
  original_document <- unique(as.integer(runif(20, 0, 30)))
  number_permutations <- 1e5
  # Generate permutations
  permutations <- lime:::get_index_permutations(
    original_document,
    number_permutations
  )

  # Expected number of permutations
  expect_length(permutations, number_permutations)

  # First permutation is the original document
  expect_equal(permutations[[1]], original_document)

  # No permutation is larger than the original document
  expect_true(all(lengths(permutations) <= length(original_document)))

  # Permutations doesn't contain duplicates
  expect_true(all(unlist(lapply(permutations, function(x) {
    all(!duplicated(x))
  }))))

  # There is no empty permutation
  expect_true(sum(lengths(permutations) == 0) == 0)
})

test_that("Cosine computation is correct", {
  v <- 5:13
  m <- Matrix::Matrix(1:81, ncol = 9, sparse = TRUE)
  cos <- function(x) crossprod(v, x) / sqrt(crossprod(v) * crossprod(x))
  expect_equal(
    lime:::cosine_distance_vector_to_matrix_rows(v, m),
    apply(m, MARGIN = 1, cos)
  )
})

test_that("there is no empty generated text", {
  generated_documents <- lime:::permute_cases.character(
    cases = "this is a test ",
    n_permutations = 5e3,
    tokenization = default_tokenize,
    keep_word_position = FALSE
  )

  # There is no empty permutation
  expect_true(all(
    sapply(generated_documents$permutations, nchar, USE.NAMES = FALSE) > 0
  ))
})

test_that("Default tokenizer works for multiple documents", {
  r <- default_tokenize(c("    this is a test.", "this is another       test."))
  expect_equal(r, c("this", "is", "a", "test", "this", "is", "another", "test"))
})