acronymize.rb

def acronymize(sentence)
  sentence.split.map { |word| word[0].upcase }.join
end

p acronymize('frequently asked questions')

acronymize_specs.rb

require_relative './acronymize.rb'

describe '#acronymize' do
  it 'it returns an string if given an empty' do
    sentence = ''
    expected = ''
    actual   = acronymize(sentence)
    expect(actual).to eq(expected)
  end

  it 'it returns FAQ if given frequently asked questions' do
    sentence = 'frequently asked questions'
    expected = 'FAQ'
    actual   = acronymize(sentence)
    expect(actual).to eq(expected)
  end
end