Add feature flags on budget controllers

Although we had this feature flag in most places, we forgot to add it in
some of the controllers.

app/controllers/budgets/groups_controller.rb

@@ -1,6 +1,8 @@
 module Budgets
   class GroupsController < ApplicationController
     include InvestmentFilters
+    include FeatureFlags
+    feature_flag :budgets
 
     before_action :load_budget
     before_action :load_group

app/controllers/budgets/stats_controller.rb

@@ -1,5 +1,8 @@
 module Budgets
   class StatsController < ApplicationController
+    include FeatureFlags
+    feature_flag :budgets
+
     before_action :load_budget
     authorize_resource :budget
 

app/controllers/management/budgets/investments_controller.rb

@@ -1,5 +1,8 @@
 class Management::Budgets::InvestmentsController < Management::BaseController
   include Translatable
+  include FeatureFlags
+  feature_flag :budgets
+
   before_action :load_budget
 
   load_resource :budget

spec/controllers/budgets/groups_controller_spec.rb

@@ -4,6 +4,14 @@ describe Budgets::GroupsController do
   describe "GET show" do
     let(:group) { create(:budget_group) }
 
+    it "raises an exception when the feature is disabled" do
+      Setting["process.budgets"] = false
+
+      expect do
+        get :show, params: { budget_id: group.budget.id, id: group.id }
+      end.to raise_exception(FeatureFlags::FeatureDisabled)
+    end
+
     it "raises an error if budget slug is not found" do
       expect do
         get :show, params: { budget_id: "wrong_budget", id: group.id }

spec/controllers/budgets/stats_controller_spec.rb

@@ -2,6 +2,14 @@ require "rails_helper"
 
 describe Budgets::StatsController do
   describe "GET show" do
+    it "raises an exception when the feature is disabled" do
+      Setting["process.budgets"] = false
+
+      expect do
+        get :show, params: { budget_id: create(:budget).id }
+      end.to raise_exception(FeatureFlags::FeatureDisabled)
+    end
+
     it "raises an error if budget slug is not found" do
       expect do
         get :show, params: { budget_id: "wrong_budget" }

spec/controllers/management/budgets/investments_controller_spec.rb

@@ -8,6 +8,16 @@ describe Management::Budgets::InvestmentsController do
     login_managed_user(create(:user, :level_two))
   end
 
+  describe "GET index" do
+    it "raises an exception when the feature is disabled" do
+      Setting["process.budgets"] = false
+
+      expect do
+        get :index, params: { budget_id: create(:budget).id }
+      end.to raise_exception(FeatureFlags::FeatureDisabled)
+    end
+  end
+
   describe "GET show" do
     let(:investment) { create(:budget_investment) }