Fix `/api/v1/timelines/tag/:hashtag` allowing for unauthenticated access when public preview is disabled (#26237)

app/controllers/api/v1/timelines/tag_controller.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 class Api::V1::Timelines::TagController < Api::BaseController
+  before_action -> { doorkeeper_authorize! :read, :'read:statuses' }, only: :show, if: :require_auth?
   before_action :load_tag
   after_action :insert_pagination_headers, unless: -> { @statuses.empty? }
 
@@ -12,6 +13,10 @@ class Api::V1::Timelines::TagController < Api::BaseController
 
   private
 
+  def require_auth?
+    !Setting.timeline_preview
+  end
+
   def load_tag
     @tag = Tag.find_normalized(params[:id])
   end

spec/controllers/api/v1/timelines/tag_controller_spec.rb

@@ -6,35 +6,65 @@ describe Api::V1::Timelines::TagController do
   render_views
 
   let(:user)   { Fabricate(:user) }
+  let(:token)  { Fabricate(:accessible_access_token, resource_owner_id: user.id, scopes: 'read:statuses') }
 
   before do
     allow(controller).to receive(:doorkeeper_token) { token }
   end
 
-  context 'with a user context' do
-    let(:token) { Fabricate(:accessible_access_token, resource_owner_id: user.id) }
-
   describe 'GET #show' do
+    subject do
+      get :show, params: { id: 'test' }
+    end
+
     before do
       PostStatusService.new.call(user.account, text: 'It is a #test')
     end
 
-      it 'returns http success' do
-        get :show, params: { id: 'test' }
+    context 'when the instance allows public preview' do
+      context 'when the user is not authenticated' do
+        let(:token) { nil }
+
+        it 'returns http success', :aggregate_failures do
+          subject
+
+          expect(response).to have_http_status(200)
+          expect(response.headers['Link'].links.size).to eq(2)
+        end
+      end
+
+      context 'when the user is authenticated' do
+        it 'returns http success', :aggregate_failures do
+          subject
+
           expect(response).to have_http_status(200)
           expect(response.headers['Link'].links.size).to eq(2)
         end
       end
     end
 
-  context 'without a user context' do
-    let(:token) { Fabricate(:accessible_access_token, resource_owner_id: nil) }
+    context 'when the instance does not allow public preview' do
+      before do
+        Form::AdminSettings.new(timeline_preview: false).save
+      end
+
+      context 'when the user is not authenticated' do
+        let(:token) { nil }
+
+        it 'returns http unauthorized' do
+          subject
+
+          expect(response).to have_http_status(401)
+        end
+      end
+
+      context 'when the user is authenticated' do
+        it 'returns http success', :aggregate_failures do
+          subject
 
-    describe 'GET #show' do
-      it 'returns http success' do
-        get :show, params: { id: 'test' }
           expect(response).to have_http_status(200)
-        expect(response.headers['Link']).to be_nil
+          expect(response.headers['Link'].links.size).to eq(2)
+        end
       end
     end
   end