Add coverage for rewrite with vary username paths (#38197)

spec/requests/username_rewrites_spec.rb

@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe 'Username URL rewrites' do
+  describe 'GET /users/:username' do
+    it 'redirects to at-username page variation' do
+      get '/users/username'
+
+      expect(response)
+        .to have_http_status(301)
+        .and redirect_to('/@username')
+      expect(response.headers)
+        .to include('Vary' => 'Origin, Accept')
+    end
+  end
+
+  describe 'GET /users/:username/following' do
+    it 'redirects to at-username page variation' do
+      get '/users/username/following'
+
+      expect(response)
+        .to have_http_status(301)
+        .and redirect_to('/@username/following')
+      expect(response.headers)
+        .to include('Vary' => 'Origin, Accept')
+    end
+  end
+
+  describe 'GET /users/:username/followers' do
+    it 'redirects to at-username page variation' do
+      get '/users/username/followers'
+
+      expect(response)
+        .to have_http_status(301)
+        .and redirect_to('/@username/followers')
+      expect(response.headers)
+        .to include('Vary' => 'Origin, Accept')
+    end
+  end
+
+  describe 'GET /users/:username/statuses/:id' do
+    it 'redirects to at-username page variation' do
+      get '/users/username/statuses/123456'
+
+      expect(response)
+        .to have_http_status(301)
+        .and redirect_to('/@username/123456')
+      expect(response.headers)
+        .to include('Vary' => 'Origin, Accept')
+    end
+  end
+end