Avoid incorrect cached values

this fixes https://gitlab.com/gitlab-org/gitlab-ee/issues/12780

ee/app/services/design_management/save_designs_service.rb

@@ -34,16 +34,22 @@ module DesignManagement
     def create_and_commit_designs!
       repository.create_if_not_exists
 
-      repository_actions = files.map do |file|
-        design = collection.find_or_create_design!(filename: file.original_filename)
+      # Do not inline `build_repository_action` here!
+      # We have to do this as two *separate* calls to #map so that the call
+      # to `new_file?` does not accidentally cache the wrong data half-way
+      # through the operation.
+      corresponding_designs = files.map do |file|
+        collection.find_or_create_design!(filename: file.original_filename)
+      end
 
+      actions = files.zip(corresponding_designs).map do |(file, design)|
         build_repository_action(file, design)
       end
 
       repository.multi_action(current_user,
                               branch_name: target_branch,
                               message: commit_message,
-                              actions: repository_actions)
+                              actions: actions)
     end
 
     def build_repository_action(file, design)

ee/changelogs/unreleased/multiple-design-uploaded.yml

+---
+title: 'Fixes #12780 by avoiding incorrect cached values'
+merge_request: 14651
+type: fixed

ee/spec/services/design_management/save_designs_service_spec.rb

@@ -140,6 +140,10 @@ describe DesignManagement::SaveDesignsService do
             ]
           end
 
+          it 'returns information about both designs in the response' do
+            expect(service.execute).to include(designs: have_attributes(size: 2), status: :success)
+          end
+
           it "creates 2 designs with a single version" do
             expect { service.execute }.to change { issue.designs.count }.from(0).to(2)
             expect(DesignManagement::Version.for_designs(issue.designs).size).to eq(1)