1 files changed, 62 insertions, 0 deletions
diff --git a/spec/support/shared_examples/issuables_list_metadata_shared_examples.rb b/spec/support/shared_examples/issuables_list_metadata_shared_examples.rb
new file mode 100644
index 00000000000..f4bc6f8efa5
--- /dev/null
+++ b/spec/support/shared_examples/issuables_list_metadata_shared_examples.rb
@@ -0,0 +1,62 @@
+shared_examples 'issuables list meta-data' do |issuable_type, action = nil|
+  include ProjectForksHelper
+
+  def get_action(action, project)
+    if action
+      get action, author_id: project.creator.id
+    else
+      get :index, namespace_id: project.namespace, project_id: project
+    end
+  end
+
+  def create_issuable(issuable_type, project, source_branch:)
+    if issuable_type == :issue
+      create(issuable_type, project: project, author: project.creator)
+    else
+      create(issuable_type, source_project: project, source_branch: source_branch, author: project.creator)
+    end
+  end
+
+  before do
+    @issuable_ids = %w[fix improve/awesome].map do |source_branch|
+      create_issuable(issuable_type, project, source_branch: source_branch).id
+    end
+  end
+
+  it "creates indexed meta-data object for issuable notes and votes count" do
+    get_action(action, project)
+
+    meta_data = assigns(:issuable_meta_data)
+
+    aggregate_failures do
+      expect(meta_data.keys).to match_array(@issuable_ids)
+      expect(meta_data.values).to all(be_kind_of(Issuable::IssuableMeta))
+    end
+  end
+
+  it "avoids N+1 queries" do
+    control = ActiveRecord::QueryRecorder.new { get_action(action, project) }
+    issuable = create_issuable(issuable_type, project, source_branch: 'csv')
+
+    if issuable_type == :merge_request
+      issuable.update!(source_project: fork_project(project))
+    end
+
+    expect { get_action(action, project) }.not_to exceed_query_limit(control.count)
+  end
+
+  describe "when given empty collection" do
+    let(:project2) { create(:project, :public) }
+
+    it "doesn't execute any queries with false conditions" do
+      get_empty =
+        if action
+          proc { get action, author_id: project.creator.id }
+        else
+          proc { get :index, namespace_id: project2.namespace, project_id: project2 }
+        end
+
+      expect(&get_empty).not_to make_queries_matching(/WHERE (?:1=0|0=1)/)
+    end
+  end
+end