Copy snippet route under - scope

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

changelogs/unreleased/dz-scope-snippet-routes.yml

+---
+title: Copy snippet route under - scope
+merge_request: 35020
+author:
+type: other

config/routes.rb

@@ -262,6 +262,14 @@ Rails.application.routes.draw do
   draw :user
   draw :project
 
+  # Serve snippet routes under /-/snippets.
+  # To ensure an old unscoped routing is used for the UI we need to
+  # add prefix 'as' to the scope routing and place it below original routing.
+  # Issue https://gitlab.com/gitlab-org/gitlab/-/issues/210024
+  scope '-', as: :scoped do
+    draw :snippets
+  end
+
   root to: "root#index"
 
   get '*unmatched_route', to: 'application#route_not_found'

spec/routing/routing_spec.rb

@@ -99,6 +99,10 @@ describe SnippetsController, "routing" do
   it "to #destroy" do
     expect(delete("/snippets/1")).to route_to('snippets#destroy', id: '1')
   end
+
+  it 'to #show from scope routing' do
+    expect(get("/-/snippets/1")).to route_to('snippets#show', id: '1')
+  end
 end
 
 #            help GET /help(.:format)                 help#index