I spent 15 minutes creating a quick example...

state_spec.rb

require 'spec_helper'

# I spent 15 minutes creating a quick example for an email list...
describe "State" do

  it 'has a list of states' do
    State.respond_to?(:states)
    expect(State.states).to have_key('AK')
  end

  it '.abbrev' do
    expect(State.abbrev('Alaska')).to eq('AK')
    expect(State.abbrev('ohio')).to eq('OH')
  end

  it '.state' do
    expect(State.state('AK')).to eq('Alaska')
    expect(State.state('pa')).to eq('Pennsylvania')
  end
end


class State
  STATES = {
      'AK'=> 'Alaska',
      'PA'=> 'Pennsylvania',
      'OH'=> 'Ohio',
  }
  def self.states
    STATES
  end

  def self.abbrev(state)
    STATES.invert[state.titleize]
  end

  def self.state(abbrev)
    STATES.fetch(abbrev.upcase)
  end

end