spongebobify.rb

def spongebob_case(string)
  string.split('.').map do |sentence|
    capital = false
    sentence.strip.split.map do |word|
      if word.downcase == 'i'
        'I'
      else
        capital = false
        word.each_char.map do |char|
          if char.downcase == 'l'
            capital = false
            'L'
          elsif char.downcase == 'i'
            capital = true
            'i'
          else
            capital = !capital
            capital ? char.downcase : char.upcase
          end
        end.join('')
      end
    end.join(' ')
  end.join('. ')
end

def test_input(input, expected)
  actual = spongebob_case(input)
  unless actual == expected
    puts "expected: #{expected.inspect}"
    puts "  actual: #{actual.inspect}"
  end
end

test_input('the quick brown fox jumps over the lazy dog', 'tHe qUiCk bRoWn fOx jUmPs oVeR tHe LaZy dOg')
test_input('i love pie', 'I LoVe piE')
test_input('billiards', 'biLLiArDs')