LSP

lsp.rb

class Rectangle
  attr_reader :width, :height
  
  def initialize(width, height)
    @width = width
    @height = height
  end

  def area
    @width * @height
  end
end

class Square < Rectangle
  def initialize(side)
    super(side, side)
  end
end


describe "testing LSP" do
  it "returns right area for a rectangle" do
    rect = Rectangle.new(10, 8)
    rect.area.should == 80
  end

  it "returns the right area for a square" do
    sq = Square.new(5)
    sq.area.should == 25
  end
end