covers 'facets/array/combination'

testcase Array do

  unit :combination => "finds pairs of combinations" do
    e = [[1, 2], [1, 3], [1, 4], [2, 3], [2, 4], [3, 4]]
    a = [1,2,3,4]
    r = a.combination(2).to_a
    r.assert == e
  end

  unit :combination => "can also take a block" do
    e = [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]]
    r = []
    a = [1,2,3,4]
    a.combination(2){ |a,b| r << [a,b] }
    r.assert == e
  end

end