describe Integer, "#happy?" do
  # A007770
  @seq = [1,7,10,13,19,23,28,31,32,44,49,68,70,79,82,86,91,
          94,97,100,103,109,129,130,133,139,167,176,188,190,
          192,193,203,208,219,226,230,236,239,262,263,280,
          291,293,301,302,310,313,319,320,326,329,331,338].to_seq

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

    it "returns true for negative happy number #{-n}" do
      (-n).should_not be_happy
    end
  end

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