Inconsistent results of Draper::Decorator#decorate_collection and Draper:: Decoratable#decorate

01_test.rb

require 'rails'
require 'mongo_mapper'
require 'draper'
require 'rspec'

MongoMapper.database = 'testing'
MongoMapper::Document.send(:include, Draper::Decoratable)

class Bookmark
  include MongoMapper::Document

  key :url, String
  key :public, Boolean, default: true

  scope :valid, where(url: { :$ne => nil })
  scope :private, where(public: false)
end

class BookmarkDecorator < Draper::Decorator
  delegate_all
end

Bookmark.destroy_all

describe "draper & mongo_mapper & decorate collection" do
  before do
    Bookmark.destroy_all
    Bookmark.create url: "http://google.com/"
    Bookmark.create url: "http://apple.com/"
    Bookmark.create url: "http://amazon.com", public: false
    Bookmark.create url: nil
  end

  context "no decorate" do
    it { expect(Bookmark.valid.count).to eq 3 }
    it { expect(Bookmark.valid.private.count).to eq 1 }
  end

  context "call #decorate method for MongoMapper::Plugins::Querying::DecoratedPluckyQuery object" do
    it { expect(Bookmark.valid.decorate.count).to eq 3 }
    it { expect(Bookmark.valid.private.decorate.count).to eq 1 }
  end

  context "decorate by decorate_collection method" do
    it { expect(BookmarkDecorator.decorate_collection(Bookmark.valid).count).to eq 3 }
    it { expect(BookmarkDecorator.decorate_collection(Bookmark.valid.private).count).to eq 1 }
  end

  after do
    Bookmark.destroy_all
  end
end

02_result.txt

draper & mongo_mapper & decorate collection
  no decorate
    should eq 3
    should eq 1
  call #decorate method for MongoMapper::Plugins::Querying::DecoratedPluckyQuery object
    should eq 3 (FAILED - 1)
    should eq 1 (FAILED - 2)
  decorate by decorate_collection method
    should eq 3
    should eq 1

Failures:

  1) draper & mongo_mapper & decorate collection call #decorate method for MongoMapper::Plugins::Querying::DecoratedPluckyQuery object should eq 3
     Failure/Error: it { expect(Bookmark.valid.decorate.count).to eq 3 }
       
       expected: 3
            got: 4
       
       (compared using ==)
     # ./test.rb:40:in `block (3 levels) in <top (required)>'

  2) draper & mongo_mapper & decorate collection call #decorate method for MongoMapper::Plugins::Querying::DecoratedPluckyQuery object should eq 1
     Failure/Error: it { expect(Bookmark.valid.private.decorate.count).to eq 1 }
       
       expected: 1
            got: 4
       
       (compared using ==)
     # ./test.rb:41:in `block (3 levels) in <top (required)>'

Finished in 0.03968 seconds
6 examples, 2 failures

Failed examples:

rspec ./test.rb:40 # draper & mongo_mapper & decorate collection call #decorate method for MongoMapper::Plugins::Querying::DecoratedPluckyQuery object should eq 3
rspec ./test.rb:41 # draper & mongo_mapper & decorate collection call #decorate method for MongoMapper::Plugins::Querying::DecoratedPluckyQuery object should eq 1