added example when removed from habtm relation

spec/counter_culture_spec.rb

@@ -34,6 +34,9 @@
 require 'models/group'
 require 'models/sub_group'
 require 'models/group_item'
+require 'models/habtm_product'
+require 'models/habtm_category'
+require 'models/habtm_category_product'
 
 if ENV['DB'] == 'postgresql'
   require 'models/purchase_order'
@@ -2766,4 +2769,118 @@ def mess_up_counts
     po.reload
     expect(po.total_amount).to eq(0.0)
   end
+
+  context 'has_and_belongs_to_many' do
+    let(:create_ar_categories!) do
+      HabtmCategory.create(name: 'Category')
+      HabtmCategory.create(name: 'New Category')
+      HabtmCategory.create(name: 'Another new Category')
+    end
+
+    let(:create_ar_product!) do
+      HabtmProduct.create(name: 'Visible Product', visible: true)
+      HabtmProduct.create(name: 'Hidden / Invisible Product', visible: false)
+    end
+
+    before :each do
+      HabtmCategoriesProduct.destroy_all
+      HabtmCategory.destroy_all
+      HabtmProduct.destroy_all
+      create_ar_product!
+      create_ar_categories!
+    end
+
+    let(:product) { HabtmProduct.first }
+    let(:hidden_product) { HabtmProduct.last }
+    let(:category) { HabtmCategory.first }
+    let(:new_category) { HabtmCategory.all[1] }
+    let(:another_new_category) { HabtmCategory.all[2] }
+
+    describe 'functional test' do
+      it 'assigns product to category through <<' do
+        product.habtm_categories << category
+        expect(HabtmCategory.find(category.id).habtm_products).to include(product)
+      end
+
+      it 'assigns product to category through update' do
+        product.update!(habtm_categories: [category])
+        expect(HabtmCategory.find(category.id).habtm_products).to include(product)
+      end
+
+      it 'deletes product from category through update' do
+        product.update!(habtm_categories: [category])
+        product.update!(habtm_categories: [new_category])
+        expect(HabtmCategory.find(category.id).habtm_products).to_not include(product)
+        expect(HabtmCategory.find(new_category.id).habtm_products).to include(product)
+      end
+
+      it 'deletes properly' do
+        product.habtm_categories << category
+        product.habtm_categories.destroy(product.habtm_categories.last)
+        expect(category.reload.products_count).to eql 0
+      end
+
+      it 'count products' do
+        product.habtm_categories << category
+
+        expect(category.reload.habtm_products.count).to eql 1
+      end
+    end
+
+    describe 'adding' do
+      it 'via "<<" counts up' do
+        product.habtm_categories << category
+        expect(category.reload.products_count).to eql 1
+      end
+
+      it 'via "update" counts up' do
+        product.update(habtm_categories: [category])
+        expect(category.reload.products_count).to eql 1
+      end
+
+      it 'via "update" counts up (sanity check)' do
+        product.update(habtm_categories: [category])
+        product.update(habtm_categories: [new_category, another_new_category])
+        expect(category.reload.habtm_products.count).to eql 0
+        expect(new_category.reload.habtm_products.count).to eql 1
+        expect(another_new_category.reload.habtm_products.count).to eql 1
+      end
+    end
+
+    context 'update' do
+      before :each do
+        product.update(habtm_categories: [new_category])
+      end
+
+      it 'removes from the old category' do
+        expect(category.reload.products_count).to eql 0
+      end
+
+      it 'adds to the new category' do
+        expect(new_category.reload.products_count).to eql 1
+      end
+    end
+
+    context '<<' do
+      before :each do
+        product.habtm_categories << new_category
+      end
+
+      it 'adds to the new category' do
+        expect(new_category.reload.products_count).to eql 1
+      end
+
+      it 'removes from the old category' do
+        category.habtm_products.destroy(product)
+        expect(category.reload.products_count).to eql 0
+        expect(new_category.reload.products_count).to eql 1
+      end
+    end
+
+    it 'removes old relation via "update"' do
+      product.update(habtm_categories: [category])
+      product.update(habtm_categories: [new_category, another_new_category])
+      expect(category.reload.products_count).to eql 0
+    end
+  end
 end

spec/models/habtm_category.rb

@@ -0,0 +1,4 @@
+class HabtmCategory < ActiveRecord::Base
+  has_many :habtm_categories_products
+  has_many :habtm_products, through: :habtm_categories_products, class_name: 'HabtmProduct'
+end

spec/models/habtm_category_product.rb

@@ -0,0 +1,11 @@
+class HabtmCategoriesProduct < ActiveRecord::Base
+  belongs_to :habtm_product
+  belongs_to :habtm_category
+
+  counter_culture :habtm_category,
+                  column_name: ->(model) { model.habtm_product.visible? ? 'products_count' : nil },
+                  column_names: {
+                    HabtmProduct.visible => 'products_count'
+                  },
+                  touch: true
+end

spec/models/habtm_product.rb

@@ -0,0 +1,7 @@
+class HabtmProduct < ActiveRecord::Base
+  has_many :habtm_categories_products, dependent: :destroy
+  has_many :habtm_categories, through: :habtm_categories_products, class_name: 'HabtmCategory'
+
+  scope :visible, -> { where(visible: true) } # to be able to mix with conditional counts
+
+end

spec/schema.rb

@@ -225,6 +225,21 @@
     t.integer  "special_poly_images_count", :default => 0, :null => false
   end
 
+  create_table "habtm_products", :force => true  do |t|
+    t.string  "name", :null => false
+    t.boolean  "visible", default: false
+  end
+
+  create_table "habtm_categories", :force => true  do |t|
+    t.string  "name", :null => false
+    t.integer "products_count", default: 0, null: false
+  end
+
+  create_table "habtm_categories_products", :force => true  do |t|
+    t.integer  "habtm_category_id", :null => false
+    t.integer  "habtm_product_id", :null => false
+  end
+
   create_table "conversations", :force => true do |t|
     t.integer "candidate_id"
   end