Add E2E to create project snippet with multiple files

See https://gitlab.com/gitlab-org/quality/testcases/-/issues/1024

qa/qa/resource/project_snippet.rb

@@ -21,6 +21,13 @@ module QA
           new_snippet.set_visibility(@visibility)
           new_snippet.fill_file_name(@file_name)
           new_snippet.fill_file_content(@file_content)
+
+          @files.each.with_index(2) do |file, i|
+            new_snippet.click_add_file
+            new_snippet.fill_file_name(file[:name], i)
+            new_snippet.fill_file_content(file[:content], i)
+          end
+
           new_snippet.click_create_snippet_button
         end
       end

qa/qa/specs/features/browser_ui/3_create/snippet/create_project_snippet_with_multiple_files_spec.rb

+# frozen_string_literal: true
+
+module QA
+  RSpec.describe 'Create' do
+    describe 'Multiple file snippet' do
+      it 'creates a project snippet with multiple files', testcase: 'https://gitlab.com/gitlab-org/quality/testcases/-/issues/1024' do
+        Flow::Login.sign_in
+
+        Resource::ProjectSnippet.fabricate_via_browser_ui! do |snippet|
+          snippet.title = 'Project snippet with multiple files'
+          snippet.description = 'Snippet description'
+          snippet.visibility = 'Private'
+          snippet.file_name = '01 file name'
+          snippet.file_content = '1 file content'
+
+          # Ten is the limit of files you can have under one snippet at the moment
+          snippet.add_files do |files|
+            (2..10).each do |i|
+              files.append(name: file_name(i), content: file_content(i))
+            end
+          end
+        end
+
+        Page::Dashboard::Snippet::Show.perform do |snippet|
+          aggregate_failures 'file content verification' do
+            expect(snippet).to have_snippet_title('Project snippet with multiple files')
+            expect(snippet).to have_snippet_description('Snippet description')
+            expect(snippet).to have_visibility_type(/private/i)
+
+            (1..10).each do |i|
+              expect(snippet).to have_file_name(file_name(i), i)
+              expect(snippet).to have_file_content(file_content(i), i)
+            end
+          end
+        end
+      end
+
+      # Currently the files are returned in alphabetical order and not in the order they are created.
+      # However, it might soon change - see https://gitlab.com/gitlab-org/gitlab/-/issues/250836.
+      # By using a leading "0" we make sure the test works with either implementation.
+      def file_name(index)
+        "#{index.to_s.rjust(2, '0')} file name"
+      end
+
+      def file_content(index)
+        "#{index} file content"
+      end
+    end
+  end
+end