1 files changed, 96 insertions, 0 deletions
diff --git a/spec/requests/api/graphql/project/project_members_spec.rb b/spec/requests/api/graphql/project/project_members_spec.rb
index 466464f600c..315d44884ff 100644
--- a/spec/requests/api/graphql/project/project_members_spec.rb
+++ b/spec/requests/api/graphql/project/project_members_spec.rb
@@ -110,6 +110,102 @@ RSpec.describe 'getting project members information' do
     end
   end
 
+  context 'merge request interactions' do
+    let(:project_path) { var('ID!').with(parent_project.full_path) }
+    let(:mr_a) do
+      var('MergeRequestID!')
+        .with(global_id_of(create(:merge_request, source_project: parent_project, source_branch: 'branch-1')))
+    end
+
+    let(:mr_b) do
+      var('MergeRequestID!')
+        .with(global_id_of(create(:merge_request, source_project: parent_project, source_branch: 'branch-2')))
+    end
+
+    let(:interaction_query) do
+      <<~HEREDOC
+      edges {
+        node {
+          user {
+            id
+          }
+          mrA: #{query_graphql_field(:merge_request_interaction, { id: mr_a }, 'canMerge')}
+        }
+      }
+      HEREDOC
+    end
+
+    let(:interaction_b_query) do
+      <<~HEREDOC
+      edges {
+        node {
+          user {
+            id
+          }
+          mrA: #{query_graphql_field(:merge_request_interaction, { id: mr_a }, 'canMerge')}
+          mrB: #{query_graphql_field(:merge_request_interaction, { id: mr_b }, 'canMerge')}
+        }
+      }
+      HEREDOC
+    end
+
+    it 'avoids N+1 queries, when requesting multiple MRs' do
+      control_query = with_signature(
+        [project_path, mr_a],
+        graphql_query_for(:project, { full_path: project_path },
+                          query_graphql_field(:project_members, nil, interaction_query))
+      )
+      query_two = with_signature(
+        [project_path, mr_a, mr_b],
+        graphql_query_for(:project, { full_path: project_path },
+                          query_graphql_field(:project_members, nil, interaction_b_query))
+      )
+
+      control_count = ActiveRecord::QueryRecorder.new do
+        post_graphql(control_query, current_user: user, variables: [project_path, mr_a])
+      end
+
+      # two project members, neither of whom can merge
+      expect(can_merge(:mrA)).to eq [false, false]
+
+      expect do
+        post_graphql(query_two, current_user: user, variables: [project_path, mr_a, mr_b])
+
+        expect(can_merge(:mrA)).to eq [false, false]
+        expect(can_merge(:mrB)).to eq [false, false]
+      end.not_to exceed_query_limit(control_count)
+    end
+
+    it 'avoids N+1 queries, when more users are involved' do
+      new_user = create(:user)
+
+      query = with_signature(
+        [project_path, mr_a],
+        graphql_query_for(:project, { full_path: project_path },
+                          query_graphql_field(:project_members, nil, interaction_query))
+      )
+
+      control_count = ActiveRecord::QueryRecorder.new do
+        post_graphql(query, current_user: user, variables: [project_path, mr_a])
+      end
+
+      # two project members, neither of whom can merge
+      expect(can_merge(:mrA)).to eq [false, false]
+
+      parent_project.add_guest(new_user)
+
+      expect do
+        post_graphql(query, current_user: user, variables: [project_path, mr_a])
+
+        expect(can_merge(:mrA)).to eq [false, false, false]
+      end.not_to exceed_query_limit(control_count)
+    end
+
+    def can_merge(name)
+      graphql_data_at(:project, :project_members, :edges, :node, name, :can_merge)
+    end
+  end
+
   context 'when unauthenticated' do
     it 'returns members' do
       fetch_members(current_user: nil, project: parent_project)