1 files changed, 103 insertions, 21 deletions

diff --git a/spec/requests/api/graphql/milestone_spec.rb b/spec/requests/api/graphql/milestone_spec.rb
index 59de116fa2b..f6835936418 100644
--- a/spec/requests/api/graphql/milestone_spec.rb
+++ b/spec/requests/api/graphql/milestone_spec.rb
@@ -5,43 +5,125 @@ require 'spec_helper'
 RSpec.describe 'Querying a Milestone' do
   include GraphqlHelpers
 
-  let_it_be(:current_user) { create(:user) }
+  let_it_be(:guest) { create(:user) }
   let_it_be(:project) { create(:project) }
   let_it_be(:milestone) { create(:milestone, project: project) }
+  let_it_be(:release_a) { create(:release, project: project) }
+  let_it_be(:release_b) { create(:release, project: project) }
 
-  let(:query) do
-    graphql_query_for('milestone', { id: milestone.to_global_id.to_s }, 'title')
+  before_all do
+    milestone.releases << [release_a, release_b]
+    project.add_guest(guest)
   end
 
-  subject { graphql_data['milestone'] }
-
-  before do
-    post_graphql(query, current_user: current_user)
+  let(:expected_release_nodes) do
+    contain_exactly(a_graphql_entity_for(release_a), a_graphql_entity_for(release_b))
   end
 
-  context 'when the user has access to the milestone' do
-    before_all do
-      project.add_guest(current_user)
+  context 'when we post the query' do
+    let(:current_user) { nil }
+    let(:query) do
+      graphql_query_for('milestone', { id: milestone.to_global_id.to_s }, all_graphql_fields_for('Milestone'))
     end
 
-    it_behaves_like 'a working graphql query'
+    subject { graphql_data['milestone'] }
 
-    it { is_expected.to include('title' => milestone.name) }
-  end
+    before do
+      post_graphql(query, current_user: current_user)
+    end
 
-  context 'when the user does not have access to the milestone' do
-    it_behaves_like 'a working graphql query'
+    context 'when the user has access to the milestone' do
+      let(:current_user) { guest }
 
-    it { is_expected.to be_nil }
+      it_behaves_like 'a working graphql query'
+
+      it { is_expected.to include('title' => milestone.name) }
+
+      it 'contains release information' do
+        is_expected.to include('releases' => include('nodes' => expected_release_nodes))
+      end
+    end
+
+    context 'when the user does not have access to the milestone' do
+      it_behaves_like 'a working graphql query'
+
+      it { is_expected.to be_nil }
+    end
+
+    context 'when ID argument is missing' do
+      let(:query) do
+        graphql_query_for('milestone', {}, 'title')
+      end
+
+      it 'raises an exception' do
+        expect(graphql_errors).to include(a_hash_including('message' => "Field 'milestone' is missing required arguments: id"))
+      end
+    end
   end
 
-  context 'when ID argument is missing' do
-    let(:query) do
-      graphql_query_for('milestone', {}, 'title')
+  context 'when there are two milestones' do
+    let_it_be(:milestone_b) { create(:milestone, project: project) }
+
+    let(:current_user) { guest }
+    let(:milestone_fields) do
+      <<~GQL
+      fragment milestoneFields on Milestone {
+        #{all_graphql_fields_for('Milestone', max_depth: 1)}
+        releases { nodes { #{all_graphql_fields_for('Release', max_depth: 1)} } }
+      }
+      GQL
+    end
+
+    let(:single_query) do
+      <<~GQL
+      query ($id_a: MilestoneID!) {
+        a: milestone(id: $id_a) { ...milestoneFields }
+      }
+
+      #{milestone_fields}
+      GQL
+    end
+
+    let(:multi_query) do
+      <<~GQL
+      query ($id_a: MilestoneID!, $id_b: MilestoneID!) {
+        a: milestone(id: $id_a) { ...milestoneFields }
+        b: milestone(id: $id_b) { ...milestoneFields }
+      }
+      #{milestone_fields}
+      GQL
+    end
+
+    it 'produces correct results' do
+      r = run_with_clean_state(multi_query,
+                           context: { current_user: current_user },
+                           variables: {
+                             id_a: global_id_of(milestone).to_s,
+                             id_b: milestone_b.to_global_id.to_s
+                           })
+
+      expect(r.to_h['errors']).to be_blank
+      expect(graphql_dig_at(r.to_h, :data, :a, :releases, :nodes)).to match expected_release_nodes
+      expect(graphql_dig_at(r.to_h, :data, :b, :releases, :nodes)).to be_empty
     end
 
-    it 'raises an exception' do
-      expect(graphql_errors).to include(a_hash_including('message' => "Field 'milestone' is missing required arguments: id"))
+    it 'does not suffer from N+1 performance issues' do
+      baseline = ActiveRecord::QueryRecorder.new do
+        run_with_clean_state(single_query,
+                             context: { current_user: current_user },
+                             variables: { id_a: milestone.to_global_id.to_s })
+      end
+
+      multi = ActiveRecord::QueryRecorder.new do
+        run_with_clean_state(multi_query,
+                             context: { current_user: current_user },
+                             variables: {
+                               id_a: milestone.to_global_id.to_s,
+                               id_b: milestone_b.to_global_id.to_s
+                             })
+      end
+
+      expect(multi).not_to exceed_query_limit(baseline)
     end
   end
 end