Block directories in theme assets

lib/project_types/theme/messages/messages.rb

@@ -124,6 +124,13 @@ module Messages
           error: {
             address_binding_error: "Couldn't bind to localhost."\
               " To serve your theme, set a different address with {{command:%s theme serve --host=<address>}}",
+            invalid_subdirectory: <<~MESSAGE,
+              The presence of %s in the directory structure isn't supported.
+
+              Move any files to a parent folder, then delete unsupported subdirectories.
+
+              • Required directory structure: https://shopify.dev/themes/architecture#directory-structure-and-component-types
+            MESSAGE
           },
           serving: <<~SERVING,
 

lib/shopify_cli/theme/theme.rb

@@ -21,11 +21,11 @@ def initialize(ctx, root: nil, id: nil, name: nil, role: nil)
       end
 
       def theme_files
-        glob(["**/*.liquid", "**/*.json", "assets/*"]).uniq
+        (glob(["**/*.liquid", "**/*.json"]) + static_asset_files).uniq
       end
 
       def static_asset_files
-        glob("assets/*").reject(&:liquid?)
+        glob("assets/*", raise_on_dir: true).reject(&:liquid?)
       end
 
       def liquid_files
@@ -36,8 +36,11 @@ def json_files
         glob("**/*.json")
       end
 
-      def glob(pattern)
-        root.glob(pattern).map { |path| File.new(path, root) }
+      def glob(pattern, raise_on_dir: false)
+        root.glob(pattern).map do |path|
+          abort_if_directory!(path) if raise_on_dir
+          File.new(path, root)
+        end
       end
 
       def theme_file?(file)
@@ -218,6 +221,11 @@ def load_info_from_api
 
         self
       end
+
+      def abort_if_directory!(path)
+        return unless ::File.directory?(path)
+        @ctx.abort(@ctx.message("theme.serve.error.invalid_subdirectory", path.to_s))
+      end
     end
   end
 end

test/shopify-cli/theme/theme_test.rb

@@ -13,6 +13,18 @@ def setup
         @theme = Theme.new(@ctx, root: @root, id: "123")
       end
 
+      def test_static_assets_with_subdirectory
+        root = @root + "_with_subdirectories"
+        ctx = TestHelpers::FakeContext.new(root: root)
+        theme = Theme.new(ctx, root: root, id: "123")
+
+        io = capture_io_and_assert_raises(ShopifyCLI::Abort) do
+          theme.static_asset_paths
+        end
+        filepath = root + "/assets/assets_subdir"
+        assert_message_output(io: io, expected_content: ctx.message("theme.serve.error.invalid_subdirectory", filepath))
+      end
+
       def test_static_assets
         assert_includes(@theme.static_asset_paths, Pathname.new("assets/theme.css"))
       end