Move code owner rule validation into EE

- `Gitlab::CodeOwners::Validator` is an EE module
so anything depending on this needs to be in EE
- Inline `#codeowners_check_error`
- Use getter methods for instance vars in module

app/controllers/concerns/check_codeowner_rules.rb

-# frozen_string_literal: true
-
-module CheckCodeownerRules
-  extend ActiveSupport::Concern
-
-  def codeowners_check_error(project, branch_name, paths)
-    ::Gitlab::CodeOwners::Validator.new(project, branch_name, paths).execute
-  end
-end

app/controllers/projects/blob_controller.rb

@@ -9,7 +9,6 @@ class Projects::BlobController < Projects::ApplicationController
   include ActionView::Helpers::SanitizeHelper
   include RedirectsForMissingPathOnTree
   include SourcegraphDecorator
-  include CheckCodeownerRules
 
   prepend_before_action :authenticate_user!, only: [:edit]
 
@@ -29,7 +28,6 @@ class Projects::BlobController < Projects::ApplicationController
   before_action :editor_variables, except: [:show, :preview, :diff]
   before_action :validate_diff_params, only: :diff
   before_action :set_last_commit_sha, only: [:edit, :update]
-  before_action :validate_codeowner_rules, only: [:create, :update]
 
   before_action only: :show do
     push_frontend_feature_flag(:code_navigation, @project)
@@ -118,18 +116,7 @@ class Projects::BlobController < Projects::ApplicationController
 
   private
 
-  def validate_codeowner_rules
-    return if params[:file_path].blank?
-
-    codeowners_error = codeowners_check_error(@project, @branch_name, params[:file_path])
-
-    if codeowners_error.present?
-      flash.now[:alert] = codeowners_error
-      view = params[:action] == 'update' ? :edit : :new
-
-      render view
-    end
-  end
+  attr_reader :branch_name
 
   def blob
     @blob ||= @repository.blob_at(@commit.id, @path)
@@ -270,3 +257,5 @@ class Projects::BlobController < Projects::ApplicationController
     params.permit(:full, :since, :to, :bottom, :unfold, :offset, :indent)
   end
 end
+
+Projects::BlobController.prepend_if_ee('EE::Projects::BlobController')

ee/app/controllers/ee/projects/blob_controller.rb

+# frozen_string_literal: true
+
+module EE
+  module Projects
+    module BlobController
+      extend ActiveSupport::Concern
+
+      prepended do
+        before_action :validate_codeowner_rules, only: [:create, :update]
+      end
+
+      private
+
+      def validate_codeowner_rules
+        return if params[:file_path].blank?
+
+        codeowners_error = codeowners_check_error(project, branch_name, params[:file_path])
+
+        if codeowners_error.present?
+          flash.now[:alert] = codeowners_error
+          view = params[:action] == 'update' ? :edit : :new
+
+          render view
+        end
+      end
+
+      def codeowners_check_error(project, branch_name, paths)
+        ::Gitlab::CodeOwners::Validator.new(project, branch_name, paths).execute
+      end
+    end
+  end
+end

ee/spec/controllers/ee/projects/blob_controller_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Projects::BlobController do
+  include ProjectForksHelper
+
+  let(:project) { create(:project, :public, :repository) }
+
+  shared_examples "file matches a codeowners rule" do
+    let(:error_msg) { "Example error msg" }
+
+    it "renders to the edit page with an error msg" do
+      default_params[:file_path] = "CHANGELOG"
+
+      expect_next_instance_of(Gitlab::CodeOwners::Validator) do |validator|
+        expect(validator).to receive(:execute).and_return(error_msg)
+      end
+
+      subject
+
+      expect(flash[:alert]).to eq(error_msg)
+      expect(response).to render_template(expected_view)
+    end
+  end
+
+  describe 'POST create' do
+    let(:user) { create(:user) }
+    let(:default_params) do
+      {
+        namespace_id: project.namespace,
+        project_id: project,
+        id: 'master',
+        branch_name: 'master',
+        file_name: 'CHANGELOG',
+        content: 'Added changes',
+        commit_message: 'Create CHANGELOG'
+      }
+    end
+
+    before do
+      project.add_developer(user)
+
+      sign_in(user)
+    end
+
+    it 'redirects to blob' do
+      post :create, params: default_params
+
+      expect(response).to be_ok
+    end
+
+    it_behaves_like "file matches a codeowners rule" do
+      subject { post :create, params: default_params }
+
+      let(:expected_view) { :new }
+    end
+  end
+
+  describe 'PUT update' do
+    let(:user) { create(:user) }
+    let(:default_params) do
+      {
+        namespace_id: project.namespace,
+        project_id: project,
+        id: 'master/CHANGELOG',
+        branch_name: 'master',
+        content: 'Added changes',
+        commit_message: 'Update CHANGELOG'
+      }
+    end
+
+    def blob_after_edit_path
+      project_blob_path(project, 'master/CHANGELOG')
+    end
+
+    before do
+      project.add_maintainer(user)
+
+      sign_in(user)
+    end
+
+    it_behaves_like "file matches a codeowners rule" do
+      subject { put :update, params: default_params }
+
+      let(:expected_view) { :edit }
+    end
+  end
+end

spec/controllers/projects/blob_controller_spec.rb

@@ -250,56 +250,6 @@ describe Projects::BlobController do
     end
   end
 
-  shared_examples "file matches a codeowners rule" do
-    let(:error_msg) { "Example error msg" }
-
-    it "renders to the edit page with an error msg" do
-      default_params[:file_path] = "CHANGELOG"
-
-      expect_next_instance_of(Gitlab::CodeOwners::Validator) do |validator|
-        expect(validator).to receive(:execute).and_return(error_msg)
-      end
-
-      subject
-
-      expect(flash[:alert]).to eq(error_msg)
-      expect(response).to render_template(expected_view)
-    end
-  end
-
-  describe 'POST create' do
-    let(:user) { create(:user) }
-    let(:default_params) do
-      {
-        namespace_id: project.namespace,
-        project_id: project,
-        id: 'master',
-        branch_name: 'master',
-        file_name: 'CHANGELOG',
-        content: 'Added changes',
-        commit_message: 'Create CHANGELOG'
-      }
-    end
-
-    before do
-      project.add_developer(user)
-
-      sign_in(user)
-    end
-
-    it 'redirects to blob' do
-      post :create, params: default_params
-
-      expect(response).to be_ok
-    end
-
-    it_behaves_like "file matches a codeowners rule" do
-      subject { post :create, params: default_params }
-
-      let(:expected_view) { :new }
-    end
-  end
-
   describe 'PUT update' do
     let(:user) { create(:user) }
     let(:default_params) do
@@ -329,12 +279,6 @@ describe Projects::BlobController do
       expect(response).to redirect_to(blob_after_edit_path)
     end
 
-    it_behaves_like "file matches a codeowners rule" do
-      subject { put :update, params: default_params }
-
-      let(:expected_view) { :edit }
-    end
-
     context '?from_merge_request_iid' do
       let(:merge_request) { create(:merge_request, source_project: project, target_project: project) }
       let(:mr_params) { default_params.merge(from_merge_request_iid: merge_request.iid) }