A weird implementation idea for Game of Life

gdcr2019.rb

#!/usr/bin/env ruby

require "rspec"

class God
  def kill!(cell)
    cell.sacrifice_to self
  end

  def surrender(process)
    process.call
  end
end

class Cell
  attr_reader :liveliness

  def initialize(liveliness)
    @liveliness = liveliness
  end

  def sacrifice_to(god)
    raise unless god.is_a?(God)
    seppuku = ->() {
      @liveliness = :dead
    }
    god.surrender(seppuku)
  end

  def die?(neighbor_amount)
    return neighbor_amount != 2 && neighbor_amount != 3
  end
end


describe "Game of Life" do

  describe "A fair God" do
    subject(:god) { God.new }

    describe "#kill!" do
      subject(:cell) { Cell.new(:alive) }
      it "sacrifices cell to self via killing" do
        god.kill!(cell)
        expect(cell.liveliness).to eq(:dead)
      end
    end

    describe "#surrender" do
      it "calls the parameter" do
        did_call = false
        process = ->() { did_call = true }

        god.surrender(process)

        expect(did_call).to eq(true)
      end
    end
  end

  describe "Cell" do
    context "is alive" do
      subject(:cell) { Cell.new(:alive) }

      {
        0 => true,
        1 => true,
        2 => false,
        3 => false,
        4 => true,
        5 => true,
        6 => true,
        7 => true,
        8 => true
      }.each do |neighbor_amount, dies|
        context "has #{neighbor_amount} neighbors" do
          it (dies ? "dies" : "stays alive") do
            expect(cell.die?(neighbor_amount)).to eq(dies)
          end
        end
      end

    end
  end
end