Handle milestones: nil in releases create service

This commit updates `Releases::CreateService` to handle cases where
`#execute` is passed a Hash with `milestones: nil`. In this case, the
service should behave as if `milestones: []` was passed.

app/graphql/mutations/releases/create.rb

@@ -40,12 +40,11 @@ module Mutations
 
       authorize :create_release
 
-      def resolve(project_path:, milestones: nil, assets: nil, **scalars)
+      def resolve(project_path:, assets: nil, **scalars)
         project = authorized_find!(full_path: project_path)
 
         params = {
           **scalars,
-          milestones: milestones.presence || [],
           assets: assets.to_h
         }.with_indifferent_access
 

app/services/releases/base_service.rb

@@ -78,7 +78,7 @@ module Releases
     end
 
     def param_for_milestone_titles_provided?
-      params.key?(:milestones)
+      !!params[:milestones]
     end
 
     def execute_hooks(release, action = 'create')

spec/services/releases/create_service_spec.rb

@@ -167,9 +167,15 @@ RSpec.describe Releases::CreateService do
       end
     end
 
-    context 'when no milestone is passed in' do
+    context 'no milestone association behavior' do
+      let(:title_1) { 'v1.0' }
+      let(:title_2) { 'v1.0-rc' }
+      let!(:milestone_1) { create(:milestone, :active, project: project, title: title_1) }
+      let!(:milestone_2) { create(:milestone, :active, project: project, title: title_2) }
+
+      context 'when no milestones parameter is passed' do
         it 'creates a release without a milestone tied to it' do
-        expect(params.key?(:milestones)).to be_falsey
+          expect(service.param_for_milestone_titles_provided?).to be_falsey
 
           service.execute
           release = project.releases.last
@@ -182,7 +188,7 @@ RSpec.describe Releases::CreateService do
         end
       end
 
-    context 'when an empty value is passed as a milestone' do
+      context 'when an empty array is passed as the milestones parameter' do
         it 'creates a release without a milestone tied to it' do
           service = described_class.new(project, user, params.merge!({ milestones: [] }))
           service.execute
@@ -191,6 +197,19 @@ RSpec.describe Releases::CreateService do
           expect(release.milestones).to be_empty
         end
       end
+
+      context 'when nil is passed as the milestones parameter' do
+        it 'creates a release without a milestone tied to it' do
+          expect(service.param_for_milestone_titles_provided?).to be_falsey
+
+          service = described_class.new(project, user, params.merge!({ milestones: nil }))
+          service.execute
+          release = project.releases.last
+
+          expect(release.milestones).to be_empty
+        end
+      end
+    end
   end
 
   context 'Evidence collection' do