Add support for description in front matter (#297)

Merge pull request 297

README.md

@@ -62,6 +62,8 @@ Additionally, the plugin will use the following values, if present in a post's Y
 
 * `author` - The author of the post, e.g., "Dr. Jekyll". If none is given, feed readers will look to the feed author as defined in `_config.yml`. Like the feed author, this can also be an object or a reference to an author in `_data/authors.yml` (see below).
 
+* `description` - A short description of the post.
+
 ### Author information
 
 *TL;DR: In most cases, put `author: [your name]` in the document's front matter, for sites with multiple authors. If you need something more complicated, read on.*

lib/jekyll-feed/feed.xml

@@ -94,8 +94,9 @@
         <category term="{{ tag | xml_escape }}" />
       {% endfor %}
 
-      {% if post.excerpt and post.excerpt != empty %}
-        <summary type="html">{{ post.excerpt | strip_html | normalize_whitespace | xml_escape }}</summary>
+      {% assign post_summary = post.description | default: post.excerpt %}
+      {% if post_summary and post_summary != empty %}
+        <summary type="html">{{ post_summary | strip_html | normalize_whitespace | xml_escape }}</summary>
       {% endif %}
 
       {% assign post_image = post.image.path | default: post.image %}

spec/fixtures/_posts/2014-03-02-march-the-second.md

@@ -1,6 +1,8 @@
 ---
 image: https://cdn.example.org/absolute.png?h=188&w=250
 category: news
+excerpt: "ignore me"
+description: cool post
 ---
 
 March the second!

spec/jekyll-feed_spec.rb

@@ -150,6 +150,11 @@
       expect(post.summary.content).to eql("Foo")
     end
 
+    it "includes the item's description" do
+      post = feed.items[-2]
+      expect(post.summary.content).to eql("cool post")
+    end
+
     it "doesn't include the item's excerpt if blank" do
       post = feed.items.first
       expect(post.summary).to be_nil