ES: Wrap wiki search results as FoundWikiPage

This is similar to FoundBlob, but allows different policy checks.
Delegation is used instead of inheritance because it allows reuse of
SearchResults.parse_search_result.

ee/lib/elastic/latest/project_wiki_class_proxy.rb

@@ -8,6 +8,12 @@ module Elastic
       def es_type
         'wiki_blob'
       end
+
+      def elastic_search_as_wiki_page(*args)
+        elastic_search_as_found_blob(*args).map! do |blob|
+          Gitlab::Search::FoundWikiPage.new(blob)
+        end
+      end
     end
   end
 end

ee/lib/elastic/latest/project_wiki_instance_proxy.rb

@@ -8,6 +8,13 @@ module Elastic
       delegate :project, to: :target
       delegate :id, to: :project, prefix: true
 
+      # @return [Kaminari::PaginatableArray]
+      def elastic_search_as_wiki_page(query, page: 1, per: 20, options: {})
+        options = repository_specific_options(options)
+
+        self.class.elastic_search_as_wiki_page(query, page: page, per: per, options: options)
+      end
+
       private
 
       def repository_id

ee/spec/lib/elastic/latest/project_wiki_class_proxy_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Elastic::Latest::ProjectWikiClassProxy do
+  let_it_be(:project) { create(:project, :wiki_repo) }
+
+  subject { described_class.new(project.wiki.repository) }
+
+  describe '#elastic_search_as_wiki_page', :elastic do
+    let_it_be(:page) { create(:wiki_page, wiki: project.wiki) }
+
+    before do
+      stub_ee_application_setting(elasticsearch_search: true, elasticsearch_indexing: true)
+
+      Gitlab::Elastic::Indexer.new(project, wiki: true).run
+      Gitlab::Elastic::Helper.refresh_index
+    end
+
+    it 'returns FoundWikiPage', :sidekiq_inline do
+      results = subject.elastic_search_as_wiki_page('*')
+
+      expect(results.size).to eq(1)
+      expect(results).to all(be_a(Gitlab::Search::FoundWikiPage))
+
+      result = results.first
+
+      expect(result.path).to eq(page.path)
+      expect(result.startline).to eq(1)
+      expect(result.data).to include(page.content)
+      expect(result.project).to eq(project)
+    end
+  end
+end

ee/spec/lib/elastic/latest/project_wiki_instance_proxy_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Elastic::Latest::ProjectWikiInstanceProxy do
+  let_it_be(:project) { create(:project, :wiki_repo) }
+
+  subject { described_class.new(project.wiki) }
+
+  describe '#elastic_search_as_wiki_page' do
+    let(:params) do
+      {
+        page: 2,
+        per: 30,
+        options: { foo: :bar }
+      }
+    end
+
+    it 'provides repository_id if not provided' do
+      expected_params = params.deep_dup
+      expected_params[:options][:repository_id] = "wiki_#{project.id}"
+
+      expect(subject.class).to receive(:elastic_search_as_wiki_page).with('foo', expected_params)
+
+      subject.elastic_search_as_wiki_page('foo', params)
+    end
+
+    it 'uses provided repository_id' do
+      params[:options][:repository_id] = "wiki_63"
+
+      expect(subject.class).to receive(:elastic_search_as_wiki_page).with('foo', params)
+
+      subject.elastic_search_as_wiki_page('foo', params)
+    end
+  end
+end

lib/gitlab/search/found_wiki_page.rb

+# frozen_string_literal: true
+
+# - rendering by using data purely from Elasticsearch and does not trigger Gitaly calls.
+# - allows policy check
+module Gitlab
+  module Search
+    class FoundWikiPage < SimpleDelegator
+      attr_reader :wiki
+
+      def self.declarative_policy_class
+        'WikiPagePolicy'
+      end
+
+      # @param found_blob [Gitlab::Search::FoundBlob]
+      def initialize(found_blob)
+        super
+        @wiki = found_blob.project.wiki
+      end
+
+      def to_ability_name
+        'wiki_page'
+      end
+    end
+  end
+end

spec/lib/gitlab/search/found_wiki_page_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::Search::FoundWikiPage do
+  let(:project) { create(:project, :public, :repository) }
+
+  describe 'policy' do
+    let(:project) { build(:project, :repository) }
+    let(:found_blob) { Gitlab::Search::FoundBlob.new(project: project) }
+
+    subject { described_class.new(found_blob) }
+
+    it 'works with policy' do
+      expect(Ability.allowed?(project.creator, :read_wiki_page, subject)).to be_truthy
+    end
+  end
+end