/sudoku_test.rb

require 'rubygems'
require 'test/unit'
require 'shoulda'

require 'sudoku'

class CellTest < Test::Unit::TestCase
  def create_group_with(cell, *numbers)
    g = Group.new
    g << cell
    numbers.each do |n|
      c = Cell.new
      c.number = n
      g << c
    end
    g
  end

  context 'a cell' do
    setup do
      @cell = Cell.new("C25")
    end

    should 'know its name' do
      assert_equal "C25", @cell.to_s
    end

    should 'be inspectable' do
      assert_equal "C25", @cell.inspect
    end

    should 'initially have no number' do
      assert_nil @cell.number
    end

    should 'be able to set number' do
      @cell.number = 4
      assert_equal 4, @cell.number
    end

    should 'accept a zero as no number' do
      @cell.number = 0
      assert_nil @cell.number
    end

    should 'report all numbers are available' do
      assert_equal( Set[*(1..9)], @cell.available_numbers )
    end

    context 'within a group' do
      setup do
        @group = create_group_with(@cell, 3, 4, 5)
      end

      should 'report available numbers not in the group' do
        assert_equal Set[1, 2, 6, 7, 8, 9], @cell.available_numbers
      end

      should 'report no available numbers if a number has been assigned' do
        @cell.number = 6
        assert_equal Set[], @cell.available_numbers
      end

    end
  end
end


class GroupTest < Test::Unit::TestCase
  context 'a group of cells' do
    setup do
      @group = Group.new
    end
    
    should 'exist' do
      assert_not_nil @group
    end

    context 'with cells' do
      setup do
        @cells = (1..10).map { |i| Cell.new("C#{i}") }
        @cells.each do |c| @group << c end
      end

      should 'give a list of numbers' do
        assert_equal Set[], @group.numbers
      end

      context 'with some numbers' do
        setup do
          @cells[0].number = 3
          @cells[3].number = 6
        end

        should 'give a list of the remaining missing numbers' do
          assert_equal [3, 6], @group.numbers.sort
        end
      end

    end

  end
end

module Puzzles
  Wiki =
    "53  7    " +
    "6  195   " +
    " 98    6 " +
    "8   6   3" +
    "4  8 3  1" +
    "7   2   6" +
    " 6    28 " +
    "   419  5" +
    "    8  79"

  Medium =
    " 4   7 3 " +
    "  85  1  " +
    " 15 3  9 " +
    "5   7 21 " +
    "  6   8  " +
    " 81 6   9" +
    " 2  4 57 " +
    "  7  29  " +
    " 5 7   8 "
  
  Evil =
    "  53 694 " +
    " 3 1    6" +
    "       3 " +
    "7  9     " +
    " 1  3  2 " +
    "     2  7" +
    " 6       " +
    "8    7 5 " +
    " 436 81  "
end

class BoardTest < Test::Unit::TestCase
  include Puzzles

  context 'a board' do
    setup do
      @board = Board.new
    end

    should 'be inspectable' do
      assert_match %r(^<Board \.{81}>$), @board.inspect
    end

    should 'initially give all 9 numbers for all cells' do
      @board.each do |cell|
        assert_equal((1..9).to_a, cell.available_numbers.sort)
      end
    end

    should 'parse a string representation of the puzzle' do
      @board.parse(Wiki)
      assert_equal "5 3 .  . 7 .  . . .  \n" +
        "6 . .  1 9 5  . . .  \n" +
        ". 9 8  . . .  . 6 .  \n\n" +
        "8 . .  . 6 .  . . 3  \n" +
        "4 . .  8 . 3  . . 1  \n" +
        "7 . .  . 2 .  . . 6  \n\n" +
        ". 6 .  . . .  2 8 .  \n" +
        ". . .  4 1 9  . . 5  \n" +
        ". . .  . 8 .  . 7 9  \n\n",
        @board.to_s
    end

    should 'solve the Wikipedia Puzzle' do
      board = Board.new.parse(Wiki)
      board.solve

      assert board.solved?
      assert_equal "534678912672195348198342567" +
        "859761423426853791713924856" +
        "961537284287419635345286179",
        board.encoding      
    end

    should 'solve the Wikipedia Puzzle with DOS line endings' do
      board = Board.new.parse(open("puzzles/wiki_dos.sud") { |f| f.read })
      board.solve

      assert board.solved?
      assert_equal "534678912672195348198342567" +
        "859761423426853791713924856" +
        "961537284287419635345286179",
        board.encoding      
    end

    should 'solve the Medium Puzzle' do
      board = Board.new.parse(Medium)
      board.solve

      assert board.solved?
      assert_equal "942187635368594127715236498" +
        "593478216476921853281365749" +
        "829643571137852964654719382",
        board.encoding      
    end

    should 'solve the Evil Puzzle' do
      board = Board.new.parse(Evil)
      board.solve

      assert board.solved?
      assert_equal "285376941439125786176849235" +
        "752981364618734529394562817" +
        "567213498821497653943658172",
        board.encoding      
    end

  end
end

class SudokuSolverTest < Test::Unit::TestCase
  WikiPuzzleFile = 'puzzles/wiki.sud'
      SOLUTION = %{5 3 4  6 7 8  9 1 2  
6 7 2  1 9 5  3 4 8  
1 9 8  3 4 2  5 6 7  

8 5 9  7 6 1  4 2 3  
4 2 6  8 5 3  7 9 1  
7 1 3  9 2 4  8 5 6  

9 6 1  5 3 7  2 8 4  
2 8 7  4 1 9  6 3 5  
3 4 5  2 8 6  1 7 9}
      

  def redirect_output
    old_stdout = $stdout
    $stdout = StringIO.new
    yield
    $stdout.string
  ensure
    $stdout = old_stdout
  end

  context 'a solver' do
    setup do
      @solver = SudokuSolver.new
    end

    should 'solve a puzzle' do
      result = redirect_output do
        @solver.run([WikiPuzzleFile])
      end
      assert_match(/#{SOLUTION}/, result)
    end

    should 'complain if no file given' do
      result = redirect_output do
        assert_raise(SystemExit) do
          @solver.run([])          
        end
      end
      assert_match(/Usage:/, result)
    end
  end
end