describe Integer, "#keith?" do
  # A007629
  @seq = [14,19,28,47,61,75,197,742,1104,1537,2208,2580,
          3684,4788,7385,7647,7909,31331,34285,34348,55604,
          62662,86935,93993,120284,129106,147640,156146,
          174680,183186,298320,355419,694280,925993,1084051,
          7913837,11436171,33445755,44121607].to_seq

  @seq.each do |n|
    it "returns true for Keith number #{n}" do
      n.should be_keith
    end
  end

  @seq.invert.sample(10).each do |n|
    it "returns false for non-Keith number #{n}" do
      n.should_not be_keith
    end
  end
end