Implemented the word count kata using red-refactor-green and dependency injection. I think I went wrong with the count class - it's a value object wrapping a Hash. Next time, I'll try wrapping the actual word count.

word_count1.rb

require 'rspec-given'

describe "word counter" do
  Given(:word_counter) { WordCounterFactory.new.create }
  Then { word_counter.count("one") == {"one" => 1} }
  Then { word_counter.count("one fish") == {"one" => 1, "fish" => 1} }
  Then { word_counter.count("one fish fish") == {"one" => 1, "fish" => 2} }
  Then { word_counter.count("one fish,fish") == {"one" => 1, "fish" => 2} }
  Then { word_counter.count("one fish Fish") == {"one" => 1, "fish" => 2} }
  Then { word_counter.count("one fish  Fish") == {"one" => 1, "fish" => 2} }
  Then { word_counter.count("one fish &$%Fish") == {"one" => 1, "fish" => 2} }
end

class WordCounterFactory
  def create
    parser = Parser.new(Count.new, ->(text) { text.split(/\W+/).map(&:downcase) } )
    WordCounter.new(parser)
  end
end

class WordCounter
  def initialize(parser)
    @parser = parser
  end

  def count(text)
    @parser.parse(text).to_hash
  end
end

class Parser
  def initialize(count, split_fn)
    @count = count
    @split_fn = split_fn
  end

  def parse(text)
    @split_fn.call(text).inject(@count) do |count, word|
      count.increment(word)
    end
  end
end

class Count
  def initialize(count = {})
    @count = count.to_hash
    @count.default = 0
  end

  def increment(word)
    @count[word] += 1
    Count.new(self)
  end

  def to_hash
    @count.clone
  end
end