test_task.rb

class Movie < ActiveRecord::Base
  has_many :sessions
  
  def self.next_week_list
    next_week_beginning = Date.today.at_beginning_of_week.next_week
    next_week_end = Date.today.at_end_of_week.next_week
    
    joins(:session).where("sessions.beginning_of > ? and sessions.beginning_of < ?", next_week_beginning, next_week_end)9
  end
end

class Session < ActiveRecord::Base
  belongs_to :movie
end

class Ticket < ActiveRecord::Base
  belongs_to :session
  belongs_to :user
  
  def self.buy(user_id, session_id: session_id) do
    create(user_id: user_id, session_id: session_id)
  end
  
  def check(user_id) do
    if self.user_id == user_id do
      update_attribute(:checked, true)
      true
    else
      false
    end
  end
end