Refactor based on review feedback

Cleaned up the specs and also included head_pipeline prefix to
delegated method.

app/models/merge_request.rb

@@ -295,8 +295,7 @@ class MergeRequest < ApplicationRecord
   alias_attribute :auto_merge_enabled, :merge_when_pipeline_succeeds
   alias_method :issuing_parent, :target_project
 
-  delegate :builds_with_coverage, to: :head_pipeline, allow_nil: true
-  delegate :active?, to: :head_pipeline, prefix: true, allow_nil: true
+  delegate :active?, :builds_with_coverage, to: :head_pipeline, prefix: true, allow_nil: true
   delegate :success?, :active?, to: :actual_head_pipeline, prefix: true, allow_nil: true
 
   RebaseLockTimeout = Class.new(StandardError)

app/serializers/merge_request_poll_widget_entity.rb

@@ -73,7 +73,7 @@ class MergeRequestPollWidgetEntity < Grape::Entity
     presenter(merge_request).pipeline_coverage_delta
   end
 
-  expose :builds_with_coverage, using: BuildCoverageEntity
+  expose :head_pipeline_builds_with_coverage, as: :builds_with_coverage, using: BuildCoverageEntity
 
   expose :cancel_auto_merge_path do |merge_request|
     presenter(merge_request).cancel_auto_merge_path

spec/models/ci/pipeline_spec.rb

@@ -3440,4 +3440,16 @@ RSpec.describe Ci::Pipeline, :mailer, factory_default: :keep do
       it { is_expected.to eq(Gitlab::Git::TAG_REF_PREFIX + pipeline.source_ref.to_s) }
     end
   end
+
+  describe "#builds_with_coverage" do
+    let!(:rspec) { create(:ci_build, name: 'rspec', coverage: 97.1, pipeline: pipeline) }
+    let!(:jest) { create(:ci_build, name: 'jest', coverage: 94.1, pipeline: pipeline) }
+    let!(:karma) { create(:ci_build, name: 'karma', coverage: nil, pipeline: pipeline) }
+
+    subject(:builds) { pipeline.builds_with_coverage }
+
+    it 'returns builds with coverage only' do
+      expect(builds).to match_array([rspec, jest])
+    end
+  end
 end

spec/models/merge_request_spec.rb

@@ -4113,27 +4113,13 @@ RSpec.describe MergeRequest, factory_default: :keep do
     end
   end
 
-  describe '#builds_with_coverage' do
-    let(:builds) { subject.builds_with_coverage }
-    let(:head_pipeline) { create(:ci_empty_pipeline) }
-    let!(:rspec) { create(:ci_build, name: 'rspec', coverage: 97.1, pipeline: head_pipeline) }
-    let!(:jest) { create(:ci_build, name: 'jest', coverage: 94.1, pipeline: head_pipeline) }
-    let!(:karma) { create(:ci_build, name: 'karma', coverage: nil, pipeline: head_pipeline) }
-
-    context 'when head_pipeline is not present' do
-      it 'returns nil' do
-        expect(builds).to be_nil
-      end
-    end
-
-    context 'when head_pipeline is present' do
-      before do
-        subject.update_attribute(:head_pipeline_id, head_pipeline.id)
-      end
-
-      it 'returns the builds with coverage' do
-        expect(builds).to match_array([rspec, jest])
-      end
+  describe '#head_pipeline_builds_with_coverage' do
+    it do
+      is_expected
+        .to delegate_method(:builds_with_coverage)
+        .to(:head_pipeline)
+        .with_prefix
+        .with_arguments(allow_nil: true)
     end
   end
 end

spec/serializers/merge_request_poll_widget_entity_spec.rb

@@ -296,7 +296,7 @@ RSpec.describe MergeRequestPollWidgetEntity do
     end
 
     before do
-      allow(resource).to receive(:builds_with_coverage).and_return(builds)
+      allow(resource).to receive(:head_pipeline_builds_with_coverage).and_return(builds)
     end
 
     it 'serializes the builds with coverage' do