Allow FoundBlob to access language from gitattributes

Extract language_from_git_attributes as a concern so it can
ben included in two blob classes.

app/models/blob.rb

@@ -3,6 +3,7 @@
 # Blob is a Rails-specific wrapper around Gitlab::Git::Blob, SnippetBlob and Ci::ArtifactBlob
 class Blob < SimpleDelegator
   include Presentable
+  include BlobLanguageFromGitAttributes
 
   CACHE_TIME = 60 # Cache raw blobs referred to by a (mutable) ref for 1 minute
   CACHE_TIME_IMMUTABLE = 3600 # Cache blobs referred to by an immutable reference for 1 hour
@@ -180,13 +181,6 @@ class Blob < SimpleDelegator
     Gitlab::FileDetector.type_of(path) || Gitlab::FileDetector.type_of(name)
   end
 
-  def language_from_gitattributes
-    return nil unless project
-
-    repository = project.repository
-    repository.gitattribute(path, 'gitlab-language')
-  end
-
   def video?
     UploaderHelper::VIDEO_EXT.include?(extension)
   end

app/models/concerns/blob_language_from_git_attributes.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+# Applicable for blob classes with project attribute
+module BlobLanguageFromGitAttributes
+  extend ActiveSupport::Concern
+
+  def language_from_gitattributes
+    return nil unless project
+
+    repository = project.repository
+    repository.gitattribute(path, 'gitlab-language')
+  end
+end

lib/gitlab/project_search_results.rb

@@ -82,7 +82,7 @@ module Gitlab
         ref: ref,
         startline: startline,
         data: data.join,
-        project_id: project ? project.id : nil
+        project: project
       )
     end
 

lib/gitlab/search_results.rb

@@ -5,8 +5,9 @@ module Gitlab
     class FoundBlob
       include EncodingHelper
       include Presentable
+      include BlobLanguageFromGitAttributes
 
-      attr_reader :id, :filename, :basename, :ref, :startline, :data, :project_id
+      attr_reader :id, :filename, :basename, :ref, :startline, :data, :project
 
       def initialize(opts = {})
         @id = opts.fetch(:id, nil)
@@ -16,17 +17,15 @@ module Gitlab
         @startline = opts.fetch(:startline, nil)
         @data = encode_utf8(opts.fetch(:data, nil))
         @per_page = opts.fetch(:per_page, 20)
-        @project_id = opts.fetch(:project_id, nil)
+        @project = opts.fetch(:project, nil)
       end
 
       def path
         filename
       end
 
-      # Since search results often contain many items,
-      # not triggering lookup can avoid n+1 queries.
-      def language_from_gitattributes
-        nil
+      def project_id
+        @project&.id
       end
 
       def present

spec/features/search/user_searches_for_wiki_pages_spec.rb

@@ -2,7 +2,7 @@ require 'spec_helper'
 
 describe 'User searches for wiki pages', :js do
   let(:user) { create(:user) }
-  let(:project) { create(:project, :wiki_repo, namespace: user.namespace) }
+  let(:project) { create(:project, :repository, :wiki_repo, namespace: user.namespace) }
   let!(:wiki_page) { create(:wiki_page, wiki: project.wiki, attrs: { title: 'test_wiki', content: 'Some Wiki content' }) }
 
   before do

spec/models/blob_spec.rb

@@ -224,22 +224,6 @@ describe Blob do
     end
   end
 
-  describe '#language_from_gitattributes' do
-    subject(:blob) { fake_blob(path: 'file.md') }
-
-    it 'returns return value from gitattribute' do
-      expect(blob.project.repository).to receive(:gitattribute).with(blob.path, 'gitlab-language').and_return('erb?parent=json')
-
-      expect(blob.language_from_gitattributes).to eq('erb?parent=json')
-    end
-
-    it 'returns nil if project is absent' do
-      allow(blob).to receive(:project).and_return(nil)
-
-      expect(blob.language_from_gitattributes).to eq(nil)
-    end
-  end
-
   describe '#simple_viewer' do
     context 'when the blob is empty' do
       it 'returns an empty viewer' do

spec/models/concerns/blob_language_from_git_attributes_spec.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe BlobLanguageFromGitAttributes do
+  include FakeBlobHelpers
+
+  let(:project) { build(:project, :repository) }
+
+  describe '#language_from_gitattributes' do
+    subject(:blob) { fake_blob(path: 'file.md') }
+
+    it 'returns return value from gitattribute' do
+      expect(blob.project.repository).to receive(:gitattribute).with(blob.path, 'gitlab-language').and_return('erb?parent=json')
+
+      expect(blob.language_from_gitattributes).to eq('erb?parent=json')
+    end
+
+    it 'returns nil if project is absent' do
+      allow(blob).to receive(:project).and_return(nil)
+
+      expect(blob.language_from_gitattributes).to eq(nil)
+    end
+  end
+end