Added restriction for guest on Release page

Added restriction for evidence in Release API.
Added restriction in Release controller.
Added relevant tests.

app/controllers/projects/releases_controller.rb

@@ -10,6 +10,7 @@ class Projects::ReleasesController < Projects::ApplicationController
     push_frontend_feature_flag(:release_evidence_collection, project)
   end
   before_action :authorize_update_release!, only: %i[edit update]
+  before_action :authorize_download_code!, only: [:evidence]
 
   def index
     respond_to do |format|

lib/api/entities.rb

@@ -1319,7 +1319,7 @@ module API
       expose :milestones, using: Entities::Milestone, if: -> (release, _) { release.milestones.present? }
       expose :commit_path, expose_nil: false
       expose :tag_path, expose_nil: false
-      expose :evidence_sha, expose_nil: false
+      expose :evidence_sha, expose_nil: false, if: ->(_, _) { can_download_code? }
       expose :assets do
         expose :assets_count, as: :count do |release, _|
           assets_to_exclude = can_download_code? ? [] : [:sources]
@@ -1329,7 +1329,7 @@ module API
         expose :links, using: Entities::Releases::Link do |release, options|
           release.links.sorted
         end
-        expose :evidence_file_path, expose_nil: false
+        expose :evidence_file_path, expose_nil: false, if: ->(_, _) { can_download_code? }
       end
       expose :_links do
         expose :merge_requests_url, expose_nil: false

spec/controllers/projects/releases_controller_spec.rb

@@ -184,19 +184,37 @@ describe Projects::ReleasesController do
       sign_in(user)
     end
 
-    it 'returns the correct evidence summary as a json' do
-      subject
+    context 'when the user is a developer' do
+      it 'returns the correct evidence summary as a json' do
+        subject
+
+        expect(json_response).to eq(release.evidence.summary)
+      end
 
-      expect(json_response).to eq(release.evidence.summary)
+      context 'when the release was created before evidence existed' do
+        it 'returns an empty json' do
+          release.evidence.destroy
+
+          subject
+
+          expect(json_response).to eq({})
+        end
+      end
     end
 
-    context 'when the release was created before evidence existed' do
-      it 'returns an empty json' do
-        release.evidence.destroy
+    context 'when the user is a guest for the project' do
+      before do
+        project.add_guest(user)
+      end
 
-        subject
+      context 'if the project is private' do
+        let(:project) { private_project }
+
+        it_behaves_like 'not found'
+      end
 
-        expect(json_response).to eq({})
+      context 'if the project is public' do
+        it_behaves_like 'successful request'
       end
     end
   end