require 'tsort'
require 'test/unit'

class TSortHash < Hash # :nodoc:
  include TSort
  alias tsort_each_node each_key
  def tsort_each_child(node, &block)
    fetch(node).each(&block)
  end
end

class TSortArray < Array # :nodoc:
  include TSort
  alias tsort_each_node each_index
  def tsort_each_child(node, &block)
    fetch(node).each(&block)
  end
end

class TSortTest < Test::Unit::TestCase # :nodoc:
  def test_dag
    h = TSortHash[{1=>[2, 3], 2=>[3], 3=>[]}]
    assert_equal([3, 2, 1], h.tsort)
    assert_equal([[3], [2], [1]], h.strongly_connected_components)
  end

  def test_cycle
    h = TSortHash[{1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}]
    assert_equal([[4], [2, 3], [1]],
      h.strongly_connected_components.map {|nodes| nodes.sort})
    assert_raise(TSort::Cyclic) { h.tsort }
  end

  def test_array
    a = TSortArray[[1], [0], [0], [2]]
    assert_equal([[0, 1], [2], [3]],
      a.strongly_connected_components.map {|nodes| nodes.sort})

    a = TSortArray[[], [0]]
    assert_equal([[0], [1]],
      a.strongly_connected_components.map {|nodes| nodes.sort})
  end

  def test_noclass
    g = {1=>[2], 2=>[3, 4], 3=>[2], 4=>[]}
    each_child = lambda {|n, &b| g[n].each(&b) }
    r = []
    TSort.each_strongly_connected_component_from(1, each_child) {|scc|
      r << scc
    }
    assert_equal([[4], [2, 3], [1]], r)
  end
end