Merge branch 'sh-fix-mr-redirects' into 'master'

Fix merge request redirects going to /commits page

See merge request gitlab-org/gitlab!16705

config/routes/project.rb

@@ -239,8 +239,9 @@ constraints(::Constraints::ProjectUrlConstrainer.new) do
         end
       end
 
-      resources :merge_requests, concerns: :awardable, except: [:new, :create], constraints: { id: /\d+/ } do
+      resources :merge_requests, concerns: :awardable, except: [:new, :create, :show], constraints: { id: /\d+/ } do
         member do
+          get :show # Insert this first to ensure redirections using merge_requests#show match this route
           get :commit_change_content
           post :merge
           post :cancel_auto_merge

ee/changelogs/unreleased/sh-fix-mr-redirects.yml

+---
+title: Fix merge request redirects going to /commits page
+merge_request: 16705
+author:
+type: fixed

spec/controllers/projects/merge_requests_controller_spec.rb

@@ -78,6 +78,40 @@ describe Projects::MergeRequestsController do
           expect(response).to be_successful
         end
       end
+
+      context 'when project has moved' do
+        let(:new_project) { create(:project) }
+
+        before do
+          project.route.destroy
+          new_project.redirect_routes.create!(path: project.full_path)
+          new_project.add_developer(user)
+        end
+
+        it 'redirects from an old merge request correctly' do
+          get :show,
+              params: {
+                namespace_id: project.namespace,
+                project_id: project,
+                id: merge_request
+              }
+
+          expect(response).to redirect_to(project_merge_request_path(new_project, merge_request))
+          expect(response).to have_gitlab_http_status(302)
+        end
+
+        it 'redirects from an old merge request commits correctly' do
+          get :commits,
+              params: {
+                namespace_id: project.namespace,
+                project_id: project,
+                id: merge_request
+              }
+
+          expect(response).to redirect_to(commits_project_merge_request_path(new_project, merge_request))
+          expect(response).to have_gitlab_http_status(302)
+        end
+      end
     end
 
     context 'when user is setting notes filters' do