Add toggle_subscription action to Groups::LabelsController

app/controllers/groups/labels_controller.rb

 class Groups::LabelsController < Groups::ApplicationController
+  include ToggleSubscriptionAction
+
   before_action :label, only: [:edit, :update, :destroy]
   before_action :authorize_admin_labels!, only: [:new, :create, :edit, :update, :destroy]
   before_action :save_previous_label_path, only: [:edit]
@@ -69,6 +71,11 @@ class Groups::LabelsController < Groups::ApplicationController
   def label
     @label ||= @group.labels.find(params[:id])
   end
+  alias_method :subscribable_resource, :label
+
+  def subscribable_project
+    nil
+  end
 
   def label_params
     params.require(:label).permit(:title, :description, :color)

config/routes/group.rb

@@ -30,7 +30,10 @@ scope(path: 'groups/:group_id', module: :groups, as: :group) do
 
   resource :avatar, only: [:destroy]
   resources :milestones, constraints: { id: /[^\/]+/ }, only: [:index, :show, :update, :new, :create]
-  resources :labels, except: [:show], constraints: { id: /\d+/ }
+
+  resources :labels, except: [:show], constraints: { id: /\d+/ } do
+    post :toggle_subscription, on: :member
+  end
 end
 
 # Must be last route in this file

spec/controllers/groups/labels_controller_spec.rb

+require 'spec_helper'
+
+describe Groups::LabelsController do
+  let(:group) { create(:group) }
+  let(:user)  { create(:user) }
+
+  before do
+    group.add_owner(user)
+
+    sign_in(user)
+  end
+
+  describe 'POST #toggle_subscription' do
+    it 'allows user to toggle subscription on group labels' do
+      label = create(:group_label, group: group)
+
+      post :toggle_subscription, group_id: group.to_param, id: label.to_param
+
+      expect(response).to have_http_status(200)
+    end
+  end
+end