Add JSON responder at `#index` endpoint in feature flag controller

ee/app/controllers/projects/feature_flags_controller.rb

@@ -10,9 +10,23 @@ class Projects::FeatureFlagsController < Projects::ApplicationController
   before_action :feature_flag, only: [:edit, :update, :destroy]
 
   def index
-    @feature_flags = project.operations_feature_flags
-      .ordered
-      .page(params[:page]).per(30)
+    @feature_flags = FeatureFlagsFinder
+      .new(project, current_user, scope: params[:scope])
+      .execute
+      .page(params[:page])
+      .per(30)
+
+    respond_to do |format|
+      format.html
+      format.json do
+        Gitlab::PollingInterval.set_header(response, interval: 10_000)
+
+        render json: FeatureFlagSerializer
+          .new(project: @project, current_user: @current_user)
+          .with_pagination(request, response)
+          .represent(@feature_flags)
+      end
+    end
   end
 
   def new

ee/app/finders/feature_flags_finder.rb

+# frozen_string_literal: true
+
+class FeatureFlagsFinder
+  attr_reader :project, :feature_flags, :params, :current_user
+
+  def initialize(project, current_user, params = {})
+    @project = project
+    @current_user = current_user
+    @feature_flags = project.operations_feature_flags
+    @params = params
+  end
+
+  def execute
+    unless Ability.allowed?(current_user, :read_feature_flag, project)
+      return Operations::FeatureFlag.none
+    end
+
+    items = feature_flags
+    items = by_scope(items)
+    items.ordered
+  end
+
+  private
+
+  def by_scope(items)
+    case params[:scope]
+    when 'enabled'
+      items.enabled
+    when 'disabled'
+      items.disabled
+    else
+      items
+    end
+  end
+end

ee/app/models/operations/feature_flag.rb

@@ -18,6 +18,8 @@ module Operations
     validates :description, allow_blank: true, length: 0..255
 
     scope :ordered, -> { order(:name) }
+    scope :enabled, -> { where(active: true) }
+    scope :disabled, -> { where(active: false) }
 
     def strategies
       [

ee/app/policies/operations/feature_flag_policy.rb

+# frozen_string_literal: true
+
+module Operations
+  class FeatureFlagPolicy < BasePolicy
+    delegate { @subject.project }
+  end
+end

ee/app/serializers/feature_flag_entity.rb

+# frozen_string_literal: true
+
+class FeatureFlagEntity < Grape::Entity
+  include RequestAwareEntity
+
+  expose :id
+  expose :active
+  expose :created_at
+  expose :updated_at
+  expose :name
+  expose :description
+
+  expose :edit_path, if: -> (feature_flag, _) { can_update?(feature_flag) } do |feature_flag|
+    edit_project_feature_flag_path(feature_flag.project, feature_flag)
+  end
+
+  expose :destroy_path, if: -> (feature_flag, _) { can_destroy?(feature_flag) } do |feature_flag|
+    project_feature_flag_path(feature_flag.project, feature_flag)
+  end
+
+  private
+
+  def can_update?(feature_flag)
+    can?(current_user, :update_feature_flag, feature_flag)
+  end
+
+  def can_destroy?(feature_flag)
+    can?(current_user, :destroy_feature_flag, feature_flag)
+  end
+
+  def current_user
+    request.current_user
+  end
+end

ee/app/serializers/feature_flag_serializer.rb

+# frozen_string_literal: true
+
+class FeatureFlagSerializer < BaseSerializer
+  include WithPagination
+  entity FeatureFlagEntity
+end

ee/spec/controllers/projects/feature_flags_controller_spec.rb

@@ -60,6 +60,77 @@ describe Projects::FeatureFlagsController do
     end
   end
 
+  describe 'GET #index json' do
+    subject { get(:index, params: view_params, format: :json) }
+
+    let!(:feature_flag_active) do
+      create(:operations_feature_flag, project: project, active: true)
+    end
+
+    let!(:feature_flag_inactive) do
+      create(:operations_feature_flag, project: project, active: false)
+    end
+
+    it 'returns all feature flags as json response' do
+      subject
+
+      expect(json_response.count).to eq(2)
+      expect(json_response.first['name']).to eq(feature_flag_active.name)
+      expect(json_response.second['name']).to eq(feature_flag_inactive.name)
+    end
+
+    it 'returns edit path and destroy path' do
+      subject
+
+      expect(json_response.first['edit_path']).not_to be_nil
+      expect(json_response.first['destroy_path']).not_to be_nil
+    end
+
+    it 'matches json schema' do
+      subject
+
+      expect(response).to match_response_schema('feature_flags', dir: 'ee')
+    end
+
+    context 'when scope is specified' do
+      let(:view_params) do
+        { namespace_id: project.namespace, project_id: project, scope: scope }
+      end
+
+      context 'when scope is all' do
+        let(:scope) { 'all' }
+
+        it 'returns all feature flags' do
+          subject
+
+          expect(json_response.count).to eq(2)
+        end
+      end
+
+      context 'when scope is enabled' do
+        let(:scope) { 'enabled' }
+
+        it 'returns enabled feature flags' do
+          subject
+
+          expect(json_response.count).to eq(1)
+          expect(json_response.first['active']).to be_truthy
+        end
+      end
+
+      context 'when scope is disabled' do
+        let(:scope) { 'disabled' }
+
+        it 'returns disabled feature flags' do
+          subject
+
+          expect(json_response.count).to eq(1)
+          expect(json_response.first['active']).to be_falsy
+        end
+      end
+    end
+  end
+
   describe 'GET new' do
     render_views
 

ee/spec/finders/feature_flags_finder_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe FeatureFlagsFinder do
+  let(:finder) { described_class.new(project, user, params) }
+  let(:project) { create(:project) }
+  let(:user) { developer }
+  let(:developer) { create(:user) }
+  let(:reporter) { create(:user) }
+  let(:params) { {} }
+
+  before do
+    project.add_developer(developer)
+    project.add_reporter(reporter)
+
+    stub_licensed_features(feature_flags: true)
+  end
+
+  describe '#execute' do
+    subject { finder.execute }
+
+    let!(:feature_flag_1) { create(:operations_feature_flag, name: 'flag-a', project: project) }
+    let!(:feature_flag_2) { create(:operations_feature_flag, name: 'flag-b', project: project) }
+
+    it 'returns feature flags ordered by name' do
+      is_expected.to eq([feature_flag_1, feature_flag_2])
+    end
+
+    context 'when user is a reporter' do
+      let(:user) { reporter }
+
+      it 'returns an empty list' do
+        is_expected.to be_empty
+      end
+    end
+
+    context 'when scope is given' do
+      let!(:feature_flag_1) { create(:operations_feature_flag, project: project, active: true) }
+      let!(:feature_flag_2) { create(:operations_feature_flag, project: project, active: false) }
+
+      context 'when scope is enabled' do
+        let(:params) { { scope: 'enabled' } }
+
+        it 'returns active feature flag' do
+          is_expected.to eq([feature_flag_1])
+        end
+      end
+
+      context 'when scope is disabled' do
+        let(:params) { { scope: 'disabled' } }
+
+        it 'returns inactive feature flag' do
+          is_expected.to eq([feature_flag_2])
+        end
+      end
+    end
+  end
+end

ee/spec/fixtures/api/schemas/feature_flag.json

+{
+  "type": "object",
+  "required" : [
+    "id",
+    "name"
+  ],
+  "properties" : {
+    "id": { "type": "integer" },
+    "created_at": { "type": "date" },
+    "updated_at": { "type": "date" },
+    "name": { "type": "string" },
+    "active": { "type": "boolean" },
+    "description": { "type": ["string", "null"] },
+    "edit_path": { "type": ["string", "null"] },
+    "destroy_path": { "type": ["string", "null"] }
+  },
+  "additionalProperties": false
+}

ee/spec/fixtures/api/schemas/feature_flags.json

+{
+  "type": "array",
+  "items": { "$ref": "feature_flag.json" }
+}

ee/spec/serializers/feature_flag_entity_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe FeatureFlagEntity do
+  let(:feature_flag) { create(:operations_feature_flag, project: project) }
+  let(:project) { create(:project) }
+  let(:request) { double('request', current_user: user) }
+  let(:user) { create(:user) }
+  let(:entity) { described_class.new(feature_flag, request: request) }
+
+  before do
+    project.add_developer(user)
+
+    stub_licensed_features(feature_flags: true)
+  end
+
+  subject { entity.as_json }
+
+  it 'has feature flag attributes' do
+    expect(subject).to include(:id, :active, :created_at, :updated_at,
+      :description, :name, :edit_path, :destroy_path)
+  end
+end

ee/spec/serializers/feature_flag_serializer_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe FeatureFlagSerializer do
+  let(:serializer) { described_class.new(project: project, current_user: user) }
+  let(:user) { create(:user) }
+  let(:project) { create(:project) }
+  let(:feature_flags) { create_list(:operations_feature_flag, 3) }
+
+  before do
+    stub_licensed_features(feature_flags: true)
+    project.add_developer(user)
+  end
+
+  describe '#represent' do
+    subject { serializer.represent(feature_flags) }
+
+    it 'includes feature flag attributes' do
+      is_expected.to all(include(:id, :active, :created_at, :updated_at,
+        :description, :name))
+    end
+  end
+end