Add starred_by scope to Project

Add a scope to search for the projects that are starred by a certain user.

app/models/project.rb

@@ -242,6 +242,7 @@ class Project < ActiveRecord::Base
   scope :in_namespace, ->(namespace_ids) { where(namespace_id: namespace_ids) }
   scope :personal, ->(user) { where(namespace_id: user.namespace_id) }
   scope :joined, ->(user) { where('namespace_id != ?', user.namespace_id) }
+  scope :starred_by, ->(user) { joins(:users_star_projects).where('users_star_projects.user_id': user.id) }
   scope :visible_to_user, ->(user) { where(id: user.authorized_projects.select(:id).reorder(nil)) }
   scope :non_archived, -> { where(archived: false) }
   scope :for_milestones, ->(ids) { joins(:milestones).where('milestones.id' => ids).distinct }
@@ -350,7 +351,7 @@ class Project < ActiveRecord::Base
       where("projects.id IN (#{union.to_sql})")
     end
-    def search_by_visibility(level)
+    def search_by_visibility(level) # DEPRECATED: remove with API V3
       where(visibility_level: Gitlab::VisibilityLevel.string_options[level])
     end

app/models/user.rb

@@ -557,7 +557,7 @@ class User < ActiveRecord::Base
     authorized_projects(Gitlab::Access::REPORTER).where(id: projects)
   end
-  def viewable_starred_projects
+  def viewable_starred_projects # DEPRECATED: Use ProjectFinder instead. Remove together with API V3
     starred_projects.where("projects.visibility_level IN (?) OR projects.id IN (?)",
                            [Project::PUBLIC, Project::INTERNAL],
                            authorized_projects.select(:project_id))

spec/models/project_spec.rb

@@ -948,6 +948,20 @@ describe Project, models: true do
     end
   end
+  describe '.starred_by' do
+    it 'returns only projects starred by the given user' do
+      user1 = create(:user)
+      user2 = create(:user)
+      project1 = create(:empty_project)
+      project2 = create(:empty_project)
+      create(:empty_project)
+      user1.toggle_star(project1)
+      user2.toggle_star(project2)
+
+      expect(Project.starred_by(user1)).to contain_exactly(project1)
+    end
+  end
+
   describe '.visible_to_user' do
     let!(:project) { create(:empty_project, :private) }
     let!(:user)    { create(:user) }