Add size attribute to BlobEntity

app/serializers/diff_file_base_entity.rb

@@ -89,6 +89,14 @@ class DiffFileBaseEntity < Grape::Entity
 
   expose :viewer, using: DiffViewerEntity
 
+  expose :old_size do |diff_file|
+    diff_file.old_blob&.raw_size
+  end
+
+  expose :new_size do |diff_file|
+    diff_file.new_blob&.raw_size
+  end
+
   private
 
   def memoized_submodule_links(diff_file, options)

spec/serializers/blob_entity_spec.rb

@@ -15,8 +15,16 @@ describe BlobEntity do
   context 'as json' do
     subject { entity.as_json }
 
-    it 'exposes needed attributes' do
-      expect(subject).to include(:readable_text, :url)
+    it 'contains needed attributes' do
+      expect(subject).to include({
+        id: blob.id,
+        path: blob.path,
+        name: blob.name,
+        mode: "100644",
+        readable_text: true,
+        icon: "file-text-o",
+        url: "/#{project.full_path}/blob/master/bar/branch-test.txt"
+      })
     end
   end
 end

spec/serializers/diff_file_base_entity_spec.rb

@@ -5,15 +5,15 @@ require 'spec_helper'
 describe DiffFileBaseEntity do
   let(:project) { create(:project, :repository) }
   let(:repository) { project.repository }
+  let(:entity) { described_class.new(diff_file, options).as_json }
 
   context 'diff for a changed submodule' do
     let(:commit_sha_with_changed_submodule) do
       "cfe32cf61b73a0d5e9f13e774abde7ff789b1660"
     end
     let(:commit) { project.commit(commit_sha_with_changed_submodule) }
-    let(:diff_file) { commit.diffs.diff_files.to_a.last }
     let(:options) { { request: {}, submodule_links: Gitlab::SubmoduleLinks.new(repository) } }
-    let(:entity) { described_class.new(diff_file, options).as_json }
+    let(:diff_file) { commit.diffs.diff_files.to_a.last }
 
     it do
       expect(entity[:submodule]).to eq(true)
@@ -23,4 +23,15 @@ describe DiffFileBaseEntity do
       )
     end
   end
+
+  context 'contains raw sizes for the blob' do
+    let(:commit) { project.commit('png-lfs') }
+    let(:options) { { request: {} } }
+    let(:diff_file) { commit.diffs.diff_files.to_a.second }
+
+    it do
+      expect(entity[:old_size]).to eq(1219696)
+      expect(entity[:new_size]).to eq(132)
+    end
+  end
 end