Bug: Ensure HABTM associations are not incorrectly labeled n+1

lib/bullet/detector/n_plus_one_query.rb

@@ -35,6 +35,7 @@ def add_possible_objects(object_or_objects)
 
           objects = Array(object_or_objects)
           return if objects.map(&:bullet_primary_key_value).compact.empty?
+          return if objects.all? { |obj| obj.class.name =~ /^HABTM_/ }
 
           Bullet.debug(
             'Detector::NPlusOneQuery#add_possible_objects',

lib/bullet/stack_trace_filter.rb

@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+require "bundler"
 
 module Bullet
   module StackTraceFilter

spec/integration/active_record/association_spec.rb

@@ -401,6 +401,15 @@
   end
 
   describe Bullet::Detector::Association, 'has_and_belongs_to_many' do
+    context 'posts <=> deals' do
+      it 'should detect preload associations with join tables that have identifier' do
+        Post.includes(:deals).each { |post| post.deals.map(&:name) }
+        Bullet::Detector::UnusedEagerLoading.check_unused_preload_associations
+        expect(Bullet::Detector::Association).not_to be_has_unused_preload_associations
+
+        expect(Bullet::Detector::Association).to be_completely_preloading_associations
+      end
+    end
     context 'students <=> teachers' do
       it 'should detect non preload associations' do
         Student.all.each { |student| student.teachers.map(&:name) }

spec/models/deal.rb

@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class Deal < ActiveRecord::Base
+  has_and_belongs_to_many :posts
+end

spec/models/post.rb

@@ -4,6 +4,7 @@ class Post < ActiveRecord::Base
   belongs_to :category, inverse_of: :posts
   belongs_to :writer
   has_many :comments, inverse_of: :post
+  has_and_belongs_to_many :deals
 
   validates :category, presence: true
 

spec/support/sqlite_seed.rb

@@ -21,6 +21,13 @@ def seed_db
       post2 = category2.posts.create(name: 'second', writer: writer2)
       post3 = category2.posts.create(name: 'third', writer: writer2)
 
+      deal1 = Deal.new(name: 'Deal 1')
+      deal1.posts << post1
+      deal1.posts << post2
+      deal2 = Deal.new(name: 'Deal 2')
+      post1.deals << deal1
+      post1.deals << deal2
+
       comment1 = post1.comments.create(name: 'first', author: writer1)
       comment2 = post1.comments.create(name: 'first2', author: writer1)
       comment3 = post1.comments.create(name: 'first3', author: writer1)
@@ -156,6 +163,11 @@ def setup_db
           t.column :hotel_id, :integer
         end
 
+        create_table :deals_posts do |t|
+          t.column :deal_id, :integer
+          t.column :post_id, :integer
+        end
+
         create_table :documents do |t|
           t.string :name
           t.string :type

test.sh

@@ -1,5 +1,6 @@
 #bundle update rails && bundle exec rspec spec
 #BUNDLE_GEMFILE=Gemfile.mongoid bundle update mongoid && BUNDLE_GEMFILE=Gemfile.mongoid bundle exec rspec spec
+BUNDLE_GEMFILE=Gemfile.rails-6.1 bundle && BUNDLE_GEMFILE=Gemfile.rails-6.1 bundle exec rspec spec
 BUNDLE_GEMFILE=Gemfile.rails-6.0 bundle && BUNDLE_GEMFILE=Gemfile.rails-6.0 bundle exec rspec spec
 BUNDLE_GEMFILE=Gemfile.rails-5.2 bundle && BUNDLE_GEMFILE=Gemfile.rails-5.2 bundle exec rspec spec
 BUNDLE_GEMFILE=Gemfile.rails-5.1 bundle && BUNDLE_GEMFILE=Gemfile.rails-5.1 bundle exec rspec spec