Fix routing for paths starting with help and projects

Rails routes are matched by order they are specified. We can fix this by
pushing `draw :group` to be above the `draw :help` and `resources
:projects` routes.

Adds tests

changelogs/unreleased/groups_routing_priority.yml

+---
+title: Fix routing for paths starting with help and projects
+merge_request: 36048
+author:
+type: fixed

config/routes.rb

@@ -242,6 +242,8 @@ Rails.application.routes.draw do
     post :preview_markdown
   end
 
+  draw :group
+
   resources :projects, only: [:index, :new, :create]
 
   get '/projects/:id' => 'projects#resolve'
@@ -258,7 +260,6 @@ Rails.application.routes.draw do
   draw :admin
   draw :profile
   draw :dashboard
-  draw :group
   draw :user
   draw :project
 

spec/routing/group_routing_spec.rb

@@ -2,8 +2,8 @@
 
 require 'spec_helper'
 
-RSpec.describe "Groups", "routing" do
-  let(:group_path) { 'complex.group-namegit' }
+RSpec.shared_examples 'groups routing' do
+  let(:group_path) { 'projects.abc123' }
   let!(:group) { create(:group, path: group_path) }
 
   it "to #show" do
@@ -56,3 +56,23 @@ RSpec.describe "Groups", "routing" do
     expect(get('/groups/gitlabhq/-/boards')).to route_to('groups/boards#index', group_id: 'gitlabhq')
   end
 end
+
+RSpec.describe "Groups", "routing" do
+  context 'complex group path with dot' do
+    include_examples 'groups routing' do
+      let(:group_path) { 'complex.group-namegit' }
+    end
+  end
+
+  context 'group path starting with help' do
+    include_examples 'groups routing' do
+      let(:group_path) { 'help.abc123' }
+    end
+  end
+
+  context 'group path starting with projects' do
+    include_examples 'groups routing' do
+      let(:group_path) { 'projects.abc123' }
+    end
+  end
+end

spec/routing/project_routing_spec.rb

@@ -77,6 +77,10 @@ RSpec.describe 'project routing' do
   #                          DELETE /:id(.:format)          projects#destroy
   # preview_markdown_project POST   /:id/preview_markdown(.:format) projects#preview_markdown
   describe ProjectsController, 'routing' do
+    it 'to #index' do
+      expect(get('/projects')).to route_to('projects#index')
+    end
+
     it 'to #create' do
       expect(post('/projects')).to route_to('projects#create')
     end