Non-invariant example

example_spec.rb

describe "taking one down" do
    Given(:beers_on_the_wall){ BeersOnTheWall.new(beer_count) }
    When{ beers_on_the_wall.take_one_down }
    context "while we still have beers" do
      Then{ expect(beers_on_the_wall.count).to eql (beer_count - 1) }
    end
    context "when all the beers have gone" do
      Given(:beers_on_the_wall){ BeersOnTheWall.new(1) }
      # or Given{ beers_on_the_wall.beers = 1 }
      Then{ expect(beers_on_the_wall.count).to eql "no more bottles of beers on the wall"}
    end
  end