Fix: 絵文字リアクションに厳しいレートリミットが適用される問題

config/initializers/rack_attack.rb

@@ -141,8 +141,10 @@ class Rack::Attack
     req.session[:attempt_user_id] || req.params.dig('user', 'email').presence if req.post? && req.path_matches?('/auth/sign_in')
   end
 
+  API_CREATE_EMOJI_REACTION_REGEX = %r{\A/api/v1/statuses/\d+/emoji_reactions}
+
   throttle('throttle_password_change/account', limit: 10, period: 10.minutes) do |req|
-    req.warden_user_id if req.put? || (req.patch? && req.path_matches?('/auth'))
+    req.warden_user_id if (req.put? && !req.path.match?(API_CREATE_EMOJI_REACTION_REGEX)) || (req.patch? && req.path_matches?('/auth'))
   end
 
   self.throttled_responder = lambda do |request|

spec/config/initializers/rack_attack_spec.rb

@@ -7,7 +7,7 @@ describe Rack::Attack, type: :request do
     Rails.application
   end
 
-  shared_examples 'throttled endpoint' do
+  shared_context 'with throttled endpoint base' do
     before do
       # Rack::Attack periods are not rolling, so avoid flaky tests by setting the time in a way
       # to avoid crossing period boundaries.
@@ -18,6 +18,10 @@ describe Rack::Attack, type: :request do
 
       travel_to Time.zone.at((Time.now.to_i / period.seconds).to_i * period.seconds)
     end
+  end
+
+  shared_examples 'throttled endpoint' do
+    include_examples 'with throttled endpoint base'
 
     context 'when the number of requests is lower than the limit' do
       it 'does not change the request status' do
@@ -43,6 +47,28 @@ describe Rack::Attack, type: :request do
     end
   end
 
+  shared_examples 'does not throttle endpoint' do
+    include_examples 'with throttled endpoint base'
+
+    context 'when the number of requests is lower than the limit' do
+      it 'does not change the request status' do
+        limit.times do
+          request.call
+          expect(response).to_not have_http_status(429)
+        end
+      end
+    end
+
+    context 'when the number of requests is higher than the limit' do
+      it 'returns http too many requests after limit and returns to normal status after period' do
+        (limit * 2).times do |_i|
+          request.call
+          expect(response).to_not have_http_status(429)
+        end
+      end
+    end
+  end
+
   let(:remote_ip) { '1.2.3.5' }
 
   describe 'throttle excessive sign-up requests by IP address' do
@@ -145,4 +171,22 @@ describe Rack::Attack, type: :request do
 
     it_behaves_like 'throttled endpoint'
   end
+
+  describe 'throttle excessive emoji reaction requests by account' do
+    let(:user) { Fabricate(:user, email: 'user@host.example') }
+    let(:limit) { 10 }
+    let(:period) { 10.minutes }
+    let(:request) { -> { put path, headers: { 'REMOTE_ADDR' => remote_ip } } }
+    let(:status) { Fabricate(:status) }
+    let(:emoji) { Fabricate(:custom_emoji) }
+    let(:path) { "/api/v1/statuses/#{status.id}/emoji_reactions/#{emoji.shortcode}" }
+
+    before do
+      sign_in user, scope: :user
+
+      get '/'
+    end
+
+    it_behaves_like 'does not throttle endpoint'
+  end
 end