gistfile1.rb

# in the model:
  def self.all_by_date(year, month, order = [:created_at.desc])
    year = year.to_i

    start_month = month ? month.to_i : 1
    start_day   = 1
    start_date  = Date.new(year, start_month, start_day)

    end_month = month ? month.to_i : 12
    end_day   = days_in_month(year, end_month)
    end_date  = Date.new(year, end_month, end_day)

    all(:created_at => start_date..end_date, :order => order)
  end

  def self.days_in_month(year, month)
    (Date.new(year, 12, 31) << (12 - month)).day
  end

gistfile2.rb

# the failing spec:
# @attrs = {:user => User.first, :title => 'New Article', :content => 'Some content.'}
  it 'should find all articles on the given date' do
    year  = Time.now.year
    month = Time.now.month
    day   = Time.now.day
    Article.new(@attrs).save
    @article = Article.first
    @article.update_attributes(:created_at => "#{year}-#{month}-#{day}")
    @articles = Article.all_by_date(year, month)
    @articles.should_not be_empty
  end