gistfile1.rbx

require 'mini/spec'

Mini::Test.autorun

class EmptyStackError < StandardError; end

class Stack
  def initialize
    @stack = []
  end

  def empty?
    @stack.empty?
  end

  def push(obj)
    @stack << obj
  end

  def pop
    if @stack.size == 0
      raise EmptyStackError
    else
      @stack.pop
    end
  end
end

describe 'Make empty stack' do
  before do
    @obj  = Object.new
    @stack = Stack.new
  end

  it 'should be empty' do
    @stack.empty?.must_equal true
  end

  it 'can push object' do
    @stack.push @obj
    @stack.empty?.must_equal false
  end

  it 'can pop object' do
    @stack.push @obj
    @stack.pop.must_equal @obj
  end

  it 'should failurer pop when stack empty' do
    lambda { @stack.pop }.must_raise EmptyStackError
  end
end