exercism/elixir/isbn-verifier/test/isbn_verifier_test.exs

defmodule IsbnVerifierTest do
  use ExUnit.Case

  test "valid isbn number" do
    assert IsbnVerifier.isbn?("3-598-21508-8")
  end

  test "invalid isbn check digit" do
    refute IsbnVerifier.isbn?("3-598-21508-9")
  end

  test "valid isbn number with a check digit of 10" do
    assert IsbnVerifier.isbn?("3-598-21507-X")
  end

  test "check digit is a character other than X" do
    refute IsbnVerifier.isbn?("3-598-21507-A")
  end

  test "check digit in isbn is not treated as zero" do
    refute IsbnVerifier.isbn?("4-598-21507-B")
  end

  test "invalid character in isbn" do
    refute IsbnVerifier.isbn?("3-598-P1581-X")
  end

  test "X is only valid as a check digit" do
    refute IsbnVerifier.isbn?("3-598-2X507-9")
  end

  test "valid isbn without separating dashes" do
    assert IsbnVerifier.isbn?("3598215088")
  end

  test "isbn without separating dashes and X as check digit" do
    assert IsbnVerifier.isbn?("359821507X")
  end

  test "isbn without check digit and dashes" do
    refute IsbnVerifier.isbn?("359821507")
  end

  test "too long isbn and no dashes" do
    refute IsbnVerifier.isbn?("3598215078X")
  end

  test "too short isbn" do
    refute IsbnVerifier.isbn?("00")
  end

  test "isbn without check digit" do
    refute IsbnVerifier.isbn?("3-598-21507")
  end

  test "too long isbn" do
    refute IsbnVerifier.isbn?("3-598-21507-XA")
  end

  test "check digit of X should not be used for 0" do
    refute IsbnVerifier.isbn?("3-598-21515-X")
  end

  test "input is 9 characters" do
    refute IsbnVerifier.isbn?("134456729")
  end

  test "invalid characters are not ignored" do
    refute IsbnVerifier.isbn?("3132P34035")
  end

  test "invalid characters are not ignored before checking length" do
    refute IsbnVerifier.isbn?("3598P215088")
  end

  test "input is too long but contains a valid isbn" do
    refute IsbnVerifier.isbn?("98245726788")
  end

  # Test cases from international ISBN to test variable dash placement
  # Adapted from https://en.wikipedia.org/wiki/International_Standard_Book_Number#Registrant_element

  test "Qatar	NCCAH, Doha" do
    assert IsbnVerifier.isbn?("99921-58-10-7")
  end

  test "Singapore	World Scientific" do
    assert IsbnVerifier.isbn?("9971-5-0210-0")
  end

  test "Greece	Sigma Publications" do
    assert IsbnVerifier.isbn?("960-425-059-0")
  end

  test "Czech Republic; Slovakia	Taita Publishers" do
    assert IsbnVerifier.isbn?("80-902734-1-6")
  end

  test "Brazil	Companhia das Letras" do
    assert IsbnVerifier.isbn?("85-359-0277-5")
  end

  test "English-speaking area	Simon Wallenberg Press" do
    assert IsbnVerifier.isbn?("1-84356-028-3")
  end

  test "English-speaking area	Scribner" do
    assert IsbnVerifier.isbn?("0-684-84328-5")
  end

  test "English-speaking area	Frederick Ungar" do
    assert IsbnVerifier.isbn?("0-8044-2957-X")
  end

  test "English-speaking area	J. A. Allen & Co." do
    assert IsbnVerifier.isbn?("0-85131-041-9")
  end

  test "English-speaking area	Edupedia Publications Pvt Ltd." do
    assert IsbnVerifier.isbn?("93-86954-21-4")
  end

  test "English-speaking area Willmann-Bell" do
    assert IsbnVerifier.isbn?("0-943396-04-2")
  end

  test "English-speaking area	KT Publishing" do
    assert IsbnVerifier.isbn?("0-9752298-0-X")
  end
end