[frontend] Include request action validations to bs request validations

Before it wasn't possible to see why a bs request action was causing a
bs request to fail. All a user would see was 'Validation failed: Bs
request actions is invalid'.
Now the validation message would include details of the failed request
action.

This allows users to see why a request failed, eg. when forwarding a
request (related to #3730).

src/api/app/models/bs_request.rb

@@ -88,6 +88,7 @@ class SaveError < APIException
   validate :check_creator, on: [:create, :save!]
   validates :comment, length: { maximum: 65_535 }
   validates :description, length: { maximum: 65_535 }
+  validates_associated :bs_request_actions, message: ->(_, record) { record[:value].map { |r| r.errors.full_messages }.flatten.to_sentence }
 
   after_update :send_state_change
   after_commit :update_cache

src/api/spec/controllers/webui/package_controller_spec.rb

@@ -142,7 +142,10 @@
         post :submit_request, params: { project: source_project, package: package, targetproject: target_project, sourceupdate: 'invalid' }
       end
 
-      it { expect(flash[:error]).to eq('Unable to submit: Validation failed: Bs request actions is invalid') }
+      it do
+        expect(flash[:error]).to eq('Unable to submit: Validation failed: Bs request actions is invalid, ' \
+                                    'Bs request actions Sourceupdate is not included in the list')
+      end
       it { expect(response).to redirect_to(package_show_path(project: source_project, package: package)) }
       it { expect(BsRequestActionSubmit.where(target_project: target_project.name, target_package: package.name)).not_to exist }
     end

src/api/spec/models/bs_request_spec.rb

@@ -18,6 +18,20 @@
            source_package: source_package.name)
   end
 
+  context 'validations' do
+    let(:bs_request) { create(:bs_request) }
+    let(:bs_request_action) { create(:bs_request_action, bs_request: bs_request) }
+
+    it 'includes validation errors of associated bs_request_actions' do
+      # rubocop:disable Rails/SkipsModelValidations
+      bs_request_action.update_attribute(:sourceupdate, 'foo')
+      # rubocop:enable Rails/SkipsModelValidations
+      expect { bs_request.reload.save! }.to raise_error(
+        ActiveRecord::RecordInvalid, 'Validation failed: Bs request actions Sourceupdate is not included in the list'
+      )
+    end
+  end
+
   context '.new_from_xml' do
     let(:user) { create(:user) }
     let(:review_request) do