count_sentences.rb

# Write a method on String called `count_sentences` that returns the number of
# sentences in the string it is called on

class String
  def count_sentences
    # code goes here
  end
end

count_sentences_solution.rb

class String
  def count_sentences
    split(/\.|\?|!/).length  
  end
end

count_sentences_spec.rb

require './count_sentences'

describe String, "#count_sentences" do

  it  "should return the number of sentences in a string" do
    "one. two. three?".count_sentences.should eq(3)
  end

  it "should return zero if there are no sentences in a string" do
    "".count_sentences.should eq(0)
  end

end