A question about searching associations not a bug

[scopethis]

Hi, I'm just getting my head around pg_search and I have a question regarding associations.

Given the following simple setup

class Book < ActiveRecord::Base
  has_many :reviews
end

class Review < ActiveRecord::Base
  belongs_to :book
end

There is no joining table in this scenario. Just two tables: books and reviews.
If I wanted to grab all reviews and their associated book. I could do something like

Review.joins(:book).select('reviews.*', 'books.*')

This should return a list of repeated book names with their review.
I assumed I would be able to do something like:

class Review < ActiveRecord::Base
  belongs_to :book

  pg_search_scope :search, 
    against: {comment: 'A'},
    associated_against: {
       book: {name: 'B'}
    },
    using: { tsearch: { dictionary: 'english' } }
end

Review.joins(:book).select('reviews.*', 'books.*')
  .search('Harry Potter and the Deathly Hallows is a page turner.')

Is that possible? Or have i missed something?