1 files changed, 58 insertions, 0 deletions
diff --git a/spec/models/project_spec.rb b/spec/models/project_spec.rb
index 1cee494989d..49d9fd56d70 100644
--- a/spec/models/project_spec.rb
+++ b/spec/models/project_spec.rb
@@ -5291,6 +5291,64 @@ RSpec.describe Project, factory_default: :keep do
     end
   end
 
+  describe '#branch_allows_collaboration?' do
+    context 'when there are open merge requests that have their source/target branches point to each other' do
+      let_it_be(:project) { create(:project, :repository) }
+      let_it_be(:developer) { create(:user) }
+      let_it_be(:reporter) { create(:user) }
+      let_it_be(:guest) { create(:user) }
+
+      before_all do
+        create(
+          :merge_request,
+          target_project: project,
+          target_branch: 'master',
+          source_project: project,
+          source_branch: 'merge-test',
+          allow_collaboration: true
+        )
+
+        create(
+          :merge_request,
+          target_project: project,
+          target_branch: 'merge-test',
+          source_project: project,
+          source_branch: 'master',
+          allow_collaboration: true
+        )
+
+        project.add_developer(developer)
+        project.add_reporter(reporter)
+        project.add_guest(guest)
+      end
+
+      shared_examples_for 'successful check' do
+        it 'does not go into an infinite loop' do
+          expect { project.branch_allows_collaboration?(user, 'master') }
+            .not_to raise_error
+        end
+      end
+
+      context 'when user is a developer' do
+        let(:user) { developer }
+
+        it_behaves_like 'successful check'
+      end
+
+      context 'when user is a reporter' do
+        let(:user) { reporter }
+
+        it_behaves_like 'successful check'
+      end
+
+      context 'when user is a guest' do
+        let(:user) { guest }
+
+        it_behaves_like 'successful check'
+      end
+    end
+  end
+
   context 'with cross project merge requests' do
     let(:user) { create(:user) }
     let(:target_project) { create(:project, :repository) }