Set categor[y|ies] on post if they appear in site frontmatter defaults

lib/jekyll/utils.rb

@@ -35,17 +35,26 @@ module Jekyll
       #
       # Returns an array
       def pluralized_array_from_hash(hash, singular_key, plural_key)
-        if hash.has_key?(singular_key)
-          array = [hash[singular_key]] if hash[singular_key]
-        elsif hash.has_key?(plural_key)
-          case hash[plural_key]
+        array = []
+        array << value_from_singular_key(hash, singular_key)
+        array << value_from_plural_key(hash, plural_key) if array.flatten.compact.empty?
+        array.flatten.compact
+      end
+      
+      def value_from_singular_key(hash, key)
+        [hash[key]] if hash.has_key?(key) || (hash.default_proc && hash[key])
+      end
+      
+      def value_from_plural_key(hash, key)
+        if hash.has_key?(key) || (hash.default_proc && hash[key])
+          val = hash[key]
+          case val
           when String
-            array = hash[plural_key].split
+            val.split
           when Array
-            array = hash[plural_key].compact
+            val.compact
           end
         end
-        array || []
       end
 
       def transform_keys(hash)

test/source/_posts/2009-01-27-no-category.textile

@@ -0,0 +1,6 @@
+---
+layout: default
+title: Category in YAML
+---
+
+Best *post* ever

test/test_generated_site.rb

@@ -14,7 +14,7 @@ class TestGeneratedSite < Test::Unit::TestCase
     end
 
     should "ensure post count is as expected" do
-      assert_equal 41, @site.posts.size
+      assert_equal 42, @site.posts.size
     end
 
     should "insert site.posts into the index" do

test/test_post.rb

@@ -645,5 +645,61 @@ class TestPost < Test::Unit::TestCase
     end
 
   end
+  
+  context "site config with category" do
+    setup do
+      config = Jekyll::Configuration::DEFAULTS.merge({
+        'defaults' => [
+          'scope' => {
+            'path' => ''
+          },
+          'values' => {
+            'category' => 'article'
+          }
+        ]
+      })
+      @site = Site.new(config)
+    end
+
+    should "return category if post does not specify category" do
+      post = setup_post("2009-01-27-no-category.textile")
+      assert post.categories.include?('article'), "Expected post.categories to include 'article' but did not."
+    end
+    
+    should "override site category if set on post" do
+      post = setup_post("2009-01-27-category.textile")
+      assert post.categories.include?('foo'), "Expected post.categories to include 'foo' but did not."
+      assert !post.categories.include?('article'), "Did not expect post.categories to include 'article' but it did."
+    end
+  end
+
+  context "site config with categories" do
+    setup do
+      config = Jekyll::Configuration::DEFAULTS.merge({
+        'defaults' => [
+          'scope' => {
+            'path' => ''
+          },
+          'values' => {
+            'categories' => ['article']
+          }
+        ]
+      })
+      @site = Site.new(config)
+    end
+
+    should "return categories if post does not specify categories" do
+      post = setup_post("2009-01-27-no-category.textile")
+      assert post.categories.include?('article'), "Expected post.categories to include 'article' but did not."
+    end
+    
+    should "override site categories if set on post" do
+      post = setup_post("2009-01-27-categories.textile")
+      ['foo', 'bar', 'baz'].each do |category|
+        assert post.categories.include?(category), "Expected post.categories to include '#{category}' but did not."
+      end
+      assert !post.categories.include?('article'), "Did not expect post.categories to include 'article' but it did."
+    end
+  end
 
 end

test/test_utils.rb

@@ -15,9 +15,9 @@ class TestUtils < Test::Unit::TestCase
         assert_equal [], Utils.pluralized_array_from_hash(data, 'tag', 'tags')
       end
 
-      should "return empty array with matching nil singular" do
+      should "return plural array with nil singular" do
         data = { 'foo' => 'bar', 'tag' => nil, 'tags' => ['dog', 'cat'] }
-        assert_equal [], Utils.pluralized_array_from_hash(data, 'tag', 'tags')
+        assert_equal ['dog', 'cat'], Utils.pluralized_array_from_hash(data, 'tag', 'tags')
       end
 
       should "return single value array with matching singular" do