skip assets of unpublished posts and delete them if exist

lib/plugins/processor/post.js

@@ -159,7 +159,9 @@ module.exports = ctx => {
     }).filter(item => !isExcludedFile(item, ctx.config)).map(item => {
       const id = join(assetDir, item).substring(baseDirLength).replace(/\\/g, '/');
       const asset = PostAsset.findById(id);
-      if (asset) return undefined;
+
+      if (asset) return post.published === false ? asset.remove() : undefined; // delete if already exist
+      else if (post.published === false) return undefined; // skip assets for unpulished posts and
 
       return PostAsset.save({
         _id: id,
@@ -187,7 +189,7 @@ module.exports = ctx => {
     // TODO: Better post searching
     const post = Post.toArray().find(post => file.source.startsWith(post.asset_dir));
 
-    if (post != null) {
+    if (post != null && post.published) {
       return PostAsset.save({
         _id: id,
         slug: file.source.substring(post.asset_dir.length),

test/scripts/processors/post.js

@@ -826,6 +826,42 @@ describe('post', () => {
     ]);
   });
 
+  it('post - post_asset_folder enabled with unpublished posts', async () => {
+    hexo.config.post_asset_folder = true;
+
+    const body = [
+      'title: "Hello world"',
+      'published: false',
+      '---'
+    ].join('\n');
+
+    const file = newFile({
+      path: 'foo.html',
+      published: true,
+      type: 'create',
+      renderable: true
+    });
+
+    const assetId = 'source/_posts/foo/bar.jpg';
+    const assetPath = join(hexo.base_dir, assetId);
+
+    await Promise.all([
+      writeFile(file.source, body),
+      writeFile(assetPath, '')
+    ]);
+    await process(file);
+    const post = Post.findOne({ source: file.path });
+
+    post.published.should.be.false;
+    should.not.exist(PostAsset.findById(assetId));
+    post.remove();
+
+    await Promise.all([
+      unlink(file.source),
+      unlink(assetPath)
+    ]);
+  });
+
   it('post - post_asset_folder disabled', async () => {
     hexo.config.post_asset_folder = false;