fix: copyAssets and deleteExcludedAssets (#528)

__tests__/fixtures/publish_dir_1/assets/lib.css

@@ -0,0 +1 @@
+/* CSS */

__tests__/fixtures/publish_dir_1/assets/lib.js

@@ -0,0 +1 @@
+// JavaScript

__tests__/fixtures/publish_dir_1/index.html

@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Document</title>
+</head>
+<body>
+
+</body>
+</html>

__tests__/fixtures/publish_dir_1/main.css

@@ -0,0 +1 @@
+/* CSS */

__tests__/fixtures/publish_dir_1/main.js

@@ -0,0 +1 @@
+// JavaScript