You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: stream_item_grouper_spec.rb
    path of file: ./repos/onebody/spec/models
    
    the code of the file until where you have to start completion: require 'rails_helper'
require 'ostruct'

describe StreamItemGrouper, type: :model do
  describe StreamItemGrouper::Grouper do
    context 'given a list of items, 
    
  def create_stream_items(items)
    created_at = 1.hour.ago
    items.each_with_index.map do |item, index|
      created_at += 1.minute
      StreamItem.create!(
        title:           "item #{index}",
        streamable_type: 'Person',
        created_at:      created_at,
        shared:          item[:shared].nil? ? true : item[:shared]
      )
    end
  end