Merge branch 'georgekoltsov/dont-fail-project-export-when-exporting-diffs' into 'master'

Rescue exception when exporting MR diffs

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/98680



Merged-by: Tetiana Chupryna <tchupryna@gitlab.com>
Approved-by: Rodrigo Tomonari <rtomonari@gitlab.com>
Approved-by: Tetiana Chupryna <tchupryna@gitlab.com>
Co-authored-by: George Koltsov <gkoltsov@gitlab.com>

app/models/merge_request_diff_file.rb

@@ -25,6 +25,10 @@ def utf8_diff
     return '' if fetched_diff.blank?
 
     encode_utf8(fetched_diff) if fetched_diff.respond_to?(:encoding)
+  rescue StandardError => e
+    log_exception('Failed fetching merge request diff', e)
+
+    ''
   end
 
   def diff
@@ -75,15 +79,19 @@ def diff_export
 
     content
   rescue StandardError => e
+    log_exception('Cached external diff export failed', e)
+
+    diff
+  end
+
+  def log_exception(message, exception)
     log_payload = {
-      message: 'Cached external diff export failed',
+      message: message,
       merge_request_diff_file_id: id,
       merge_request_diff_id: merge_request_diff&.id
     }
 
-    Gitlab::ExceptionLogFormatter.format!(e, log_payload)
+    Gitlab::ExceptionLogFormatter.format!(exception, log_payload)
     Gitlab::AppLogger.warn(log_payload)
-
-    diff
   end
 end

spec/models/merge_request_diff_file_spec.rb

@@ -220,5 +220,25 @@
         file.utf8_diff
       end
     end
+
+    context 'when exception is raised' do
+      it 'logs exception and returns an empty string' do
+        allow(file).to receive(:diff).and_raise(StandardError, 'Error!')
+
+        expect(Gitlab::AppLogger)
+          .to receive(:warn)
+          .with(
+            a_hash_including(
+              :message => 'Failed fetching merge request diff',
+              :merge_request_diff_file_id => file.id,
+              :merge_request_diff_id => file.merge_request_diff.id,
+              'exception.class' => 'StandardError',
+              'exception.message' => 'Error!'
+            )
+          )
+
+        expect(file.utf8_diff).to eq('')
+      end
+    end
   end
 end