1 files changed, 92 insertions, 0 deletions
diff --git a/spec/lib/gitlab/mailgun/webhook_processors/failure_logger_spec.rb b/spec/lib/gitlab/mailgun/webhook_processors/failure_logger_spec.rb
new file mode 100644
index 00000000000..a2286415e96
--- /dev/null
+++ b/spec/lib/gitlab/mailgun/webhook_processors/failure_logger_spec.rb
@@ -0,0 +1,92 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Gitlab::Mailgun::WebhookProcessors::FailureLogger do
+  describe '#execute', :freeze_time, :clean_gitlab_redis_rate_limiting do
+    let(:base_payload) do
+      {
+        'id' => 'U2kZkAiuScqcMTq-8Atz-Q',
+        'event' => 'failed',
+        'recipient' => 'recipient@gitlab.com',
+        'reason' => 'bounce',
+        'delivery-status' => {
+          'code' => '421',
+          'message' => '4.4.2 mxfront9g.mail.example.com Error: timeout exceeded'
+        }
+      }
+    end
+
+    context 'on permanent failure' do
+      let(:processor) { described_class.new(base_payload.merge({ 'severity' => 'permanent' })) }
+
+      it 'logs the failure immediately' do
+        expect(Gitlab::ErrorTracking::Logger).to receive(:error).with(
+          event: 'email_delivery_failure',
+          mailgun_event_id: base_payload['id'],
+          recipient: base_payload['recipient'],
+          failure_type: 'permanent',
+          failure_reason: base_payload['reason'],
+          failure_code: base_payload['delivery-status']['code'],
+          failure_message: base_payload['delivery-status']['message']
+        )
+
+        processor.execute
+      end
+    end
+
+    context 'on temporary failure' do
+      let(:processor) { described_class.new(base_payload.merge({ 'severity' => 'temporary' })) }
+
+      before do
+        allow(Gitlab::ApplicationRateLimiter).to receive(:rate_limits)
+          .and_return(temporary_email_failure: { threshold: 1, interval: 1.minute })
+      end
+
+      context 'when threshold is not exceeded' do
+        it 'increments counter but does not log the failure' do
+          expect(Gitlab::ApplicationRateLimiter).to receive(:throttled?).with(
+            :temporary_email_failure, scope: 'recipient@gitlab.com'
+          ).and_call_original
+          expect(Gitlab::ErrorTracking::Logger).not_to receive(:error)
+
+          processor.execute
+        end
+      end
+
+      context 'when threshold is exceeded' do
+        before do
+          processor.execute
+        end
+
+        it 'increments counter and logs the failure' do
+          expect(Gitlab::ApplicationRateLimiter).to receive(:throttled?).with(
+            :temporary_email_failure, scope: 'recipient@gitlab.com'
+          ).and_call_original
+          expect(Gitlab::ErrorTracking::Logger).to receive(:error).with(
+            event: 'email_delivery_failure',
+            mailgun_event_id: base_payload['id'],
+            recipient: base_payload['recipient'],
+            failure_type: 'temporary',
+            failure_reason: base_payload['reason'],
+            failure_code: base_payload['delivery-status']['code'],
+            failure_message: base_payload['delivery-status']['message']
+          )
+
+          processor.execute
+        end
+      end
+    end
+
+    context 'on other events' do
+      let(:processor) { described_class.new(base_payload.merge({ 'event' => 'delivered' })) }
+
+      it 'does nothing' do
+        expect(Gitlab::ErrorTracking::Logger).not_to receive(:error)
+        expect(Gitlab::ApplicationRateLimiter).not_to receive(:throttled?)
+
+        processor.execute
+      end
+    end
+  end
+end