An example stack for Williamson

my_stack.rb

class MyStack
  def initialize
    @array = Array.new()
  end

  def size
    @array.size
  end

  def push(input)
    @array << input
  end

  def pop
    @array.delete_at(@array.size - 1)
  end
end

my_stack_spec.rb

require_relative "stack"

RSpec.describe MyStack do
  it "initializes to empty" do
    stack = MyStack.new()

    expect(stack.size).to eq 0
  end

  it "adds an object when pushed" do
    stack = MyStack.new()
    ten = 10

    stack.push(ten)

    expect(stack.size).to eq 1
  end

  it "removes the last object when popped" do
    stack = MyStack.new()
    ten = 10
    stack.push(ten)

    popped_object = stack.pop

    expect(popped_object).to eq ten
    expect(stack.size).to eq 0
  end
end