Challenge 2: before(:each) for Shared Setup — Solution

# stack.rb
class Stack
  def initialize
    @items = []
  end

  def push(item)
    @items.push(item)
  end

  def pop
    @items.pop
  end

  def empty?
    @items.empty?
  end
end

# spec/stack_spec.rb
require_relative "../stack"

describe Stack do
  before(:each) do
    @stack = Stack.new
  end

  it "starts empty" do
    expect(@stack.empty?).to be true
  end

  it "is no longer empty after a push" do
    @stack.push("item")
    expect(@stack.empty?).to be false
  end

  it "returns the most recently pushed item on pop" do
    @stack.push("first")
    @stack.push("second")
    expect(@stack.pop).to eq("second")
  end
end

=begin
Expected RSpec output:
Stack
  starts empty
  is no longer empty after a push
  returns the most recently pushed item on pop

3 examples, 0 failures

Notes:
- before(:each) runs before every single it block, assigning a brand new
  Stack.new to @stack each time — none of the three examples share state
  with each other, so a push in one example can never accidentally affect
  the "starts empty" example.
- Without before(:each), each it block would need to repeat
  @stack = Stack.new itself, or worse, accidentally share one @stack
  across all three examples if it were set up outside any hook.
- The three examples each test one distinct behavior (initial state,
  state after push, pop ordering), keeping each it block focused on a
  single assertion.
=end