Ensuring that layout is only set to the default value if layout is not specified

lib/jekyll/page.rb

@@ -32,7 +32,7 @@ module Jekyll
     # Returns nothing.
     def read_yaml(base, name)
       super(base, name)
-      self.data['layout'] ||= 'page'
+      self.data['layout'] = 'page' unless self.data.has_key?('layout')
       self.data
     end
 

lib/jekyll/post.rb

@@ -74,7 +74,7 @@ module Jekyll
     # Returns nothing.
     def read_yaml(base, name)
       super(base, name)
-      self.data['layout'] ||= 'post'
+      self.data['layout'] = 'post' unless self.data.has_key?('layout')
       self.data
     end
 

test/source/_posts/2013-01-12-nil-layout.textile

@@ -0,0 +1,6 @@
+---
+layout: nil
+title: No layout
+---
+
+This post has no layout.

test/source/_posts/2013-01-12-no-layout.textile

@@ -0,0 +1,5 @@
+---
+title: I have no layout
+---
+
+This post will be rendered with the "post" layout.

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 28, @site.posts.size
+      assert_equal 30, @site.posts.size
     end
 
     should "insert site.posts into the index" do

test/test_page.rb

@@ -66,6 +66,26 @@ class TestPage < Test::Unit::TestCase
         assert_equal "/about/", @page.dir
       end
     end
+    
+    context "with unspecified layout" do
+      setup do
+        @page = setup_page('contacts.html')
+      end
+
+      should "default to 'post' layout" do
+        assert_equal "page", @page.data["layout"]
+      end
+    end
+        
+    context "with specified layout of nil" do
+      setup do
+        @page = setup_page('sitemap.xml')
+      end
+
+      should "layout of nil is respected" do
+        assert_equal "nil", @page.data["layout"]
+      end
+    end
 
     context "rendering" do
       setup do

test/test_post.rb

@@ -95,7 +95,7 @@ class TestPost < Test::Unit::TestCase
         should "consume the embedded dashes" do
           @post.read_yaml(@source, @real_file)
 
-          assert_equal({"title" => "Foo --- Bar"}, @post.data)
+          assert_equal({"title" => "Foo --- Bar", "layout" => "post"}, @post.data)
           assert_equal "Triple the fun!", @post.content
         end
       end
@@ -128,6 +128,30 @@ class TestPost < Test::Unit::TestCase
           end
         end
 
+        context "with unspecified layout" do
+          setup do
+            file = '2013-01-12-no-layout.textile'
+            @post = setup_post(file)
+            @post.process(file)
+          end
+
+          should "default to 'post' layout" do
+            assert_equal "post", @post.data["layout"]
+          end
+        end
+        
+        context "with specified layout of nil" do
+          setup do
+            file = '2013-01-12-nil-layout.textile'
+            @post = setup_post(file)
+            @post.process(file)
+          end
+
+          should "layout of nil is respected" do
+            assert_equal "nil", @post.data["layout"]
+          end
+        end
+
         context "with unspecified (date) style and categories" do
           setup do
             @post.categories << "food"