Render group children using the same entity

app/serializers/group_child_entity.rb

@@ -2,10 +2,12 @@ class GroupChildEntity < Grape::Entity
   include ActionView::Helpers::NumberHelper
   include RequestAwareEntity
 
-  expose :id, :name, :description, :visibility, :full_name, :full_path, :web_url,
-         :created_at, :updated_at, :star_count, :can_edit, :type, :parent_id,
-         :children_count, :leave_path, :edit_path, :number_projects_with_delimiter,
-         :number_users_with_delimiter, :permissions, :star_count
+  expose :id, :name, :path, :description, :visibility, :full_name, :full_path, :web_url,
+         :created_at, :updated_at, :can_edit, :type, :avatar_url, :permission, :edit_path
+
+  def project?
+    object.is_a?(Project)
+  end
 
   def type
     object.class.name.downcase
@@ -14,7 +16,63 @@ class GroupChildEntity < Grape::Entity
   def can_edit
     return false unless request.respond_to?(:current_user)
 
-    can?(request.current_user, "edit_{type}", object)
+    if project?
+      can?(request.current_user, :admin_project, object)
+    else
+      can?(request.current_user, :admin_group, object)
+    end
+  end
+
+  def edit_path
+    if project?
+      edit_project_path(object)
+    else
+      edit_group_path(object)
+    end
+  end
+
+  def permission
+    if project?
+      object.project_members.find_by(user_id: request.current_user)&.human_access
+    else
+      object.group_members.find_by(user_id: request.current_user)&.human_access
+    end
+  end
+
+  # Project only attributes
+  expose :star_count,
+         if: lambda { |_instance, _options| project? }
+
+  # Group only attributes
+  expose :children_count, :leave_path, :parent_id, :number_projects_with_delimiter,
+         :number_users_with_delimiter, :project_count, :subgroup_count,
+         unless: lambda { |_instance, _options| project? }
+
+  def children_finder
+    @children_finder ||= GroupChildrenFinder.new(request.current_user, parent_group: object)
+  end
+
+  def children_count
+    @children_count ||= children_finder.total_count
+  end
+
+  def project_count
+    @project_count ||= children_finder.project_count
+  end
+
+  def subgroup_count
+    @subgroup_count ||= children_finder.subgroup_count
+  end
+
+  def leave_path
+    leave_group_group_members_path(object)
+  end
+
+  def number_projects_with_delimiter
+    number_with_delimiter(project_count)
+  end
+
+  def number_users_with_delimiter
+    number_with_delimiter(object.users.count)
   end
-  expose
 end

spec/serializers/group_child_entity_spec.rb

 require 'spec_helper'
 
 describe GroupChildEntity do
+  let(:user) { create(:user) }
   let(:request) { double('request') }
   let(:entity) { described_class.new(object, request: request) }
   subject(:json) { entity.as_json }
 
+  before do
+    allow(request).to receive(:current_user).and_return(user)
+  end
+
+  shared_examples 'group child json' do
+    it 'renders json' do
+      is_expected.not_to be_nil
+    end
+
+    %w[id
+       path
+       full_name
+       full_path
+       avatar_url
+       name
+       description
+       web_url
+       visibility
+       type
+       can_edit
+       visibility
+       edit_path
+       permission].each do |attribute|
+      it "includes #{attribute}" do
+        expect(json[attribute.to_sym]).to be_present
+      end
+    end
+  end
+
   describe 'for a project' do
-    let(:object) { build_stubbed(:project) }
+    set(:object) do
+      create(:project, :with_avatar,
+             description: 'Awesomeness')
+    end
+
+    before do
+      object.add_master(user)
+    end
 
     it 'has the correct type' do
       expect(json[:type]).to eq('project')
     end
+
+    it 'includes the star count' do
+      expect(json[:star_count]).to be_present
+    end
+
+    it_behaves_like 'group child json'
+  end
+
+  describe 'for a group', :nested_groups do
+    set(:object) do
+      create(:group, :nested, :with_avatar,
+             description: 'Awesomeness')
+    end
+
+    before do
+      object.add_owner(user)
+    end
+
+    it 'has the correct type' do
+      expect(json[:type]).to eq('group')
+    end
+
+    it 'counts projects and subgroups as children' do
+      create(:project, namespace: object)
+      create(:group, parent: object)
+
+      expect(json[:children_count]).to eq(2)
+    end
+
+    %w[children_count leave_path parent_id number_projects_with_delimiter number_users_with_delimiter project_count subgroup_count].each do |attribute|
+      it "includes #{attribute}" do
+        expect(json[attribute.to_sym]).to be_present
+      end
+    end
+
+    it_behaves_like 'group child json'
   end
 end