Add HTML export for embed elements

This is just a stub, until embedded objects are resolved
properly via OEmbed calls.

Author: dsager

lib/article_json.rb

@@ -46,3 +46,4 @@
 require_relative 'article_json/export/html/elements/image'
 require_relative 'article_json/export/html/elements/text_box'
 require_relative 'article_json/export/html/elements/quote'
+require_relative 'article_json/export/html/elements/embed'

lib/article_json/export/html/elements/base.rb

@@ -30,13 +30,14 @@ def create_text_node(text)
           class << self
             def element_classes
               {
+                text: Text,
+                paragraph: Paragraph,
                 heading: Heading,
-                image: Image,
                 list: List,
-                paragraph: Paragraph,
-                text: Text,
+                image: Image,
                 text_box: TextBox,
                 quote: Quote,
+                embed: Embed,
               }
             end
           end

lib/article_json/export/html/elements/embed.rb

@@ -0,0 +1,28 @@
+module ArticleJSON
+  module Export
+    module HTML
+      module Elements
+        class Embed < Base
+          include Shared::Caption
+
+          def build
+            create_element(:figure).tap do |figure|
+              figure.add_child(embed_node)
+              figure.add_child(caption_node(:figcaption))
+            end
+          end
+
+          private
+
+          def embed_node
+            create_element(:div, embedded_object, class: 'embed')
+          end
+
+          def embedded_object
+            "Embedded Object: #{@element.embed_type}-#{@element.embed_id}"
+          end
+        end
+      end
+    end
+  end
+end

spec/article_json/elements/export/html/base_spec.rb

@@ -63,6 +63,21 @@
       end
       it { should eq '<aside><p>Foo Bar</p><small>Baz</small></aside>' }
     end
+
+    context 'when the source element is an embedded element' do
+      let(:source_element) do
+        ArticleJSON::Elements::Embed.new(
+          embed_type: :something,
+          embed_id: 666,
+          caption: [sample_text]
+        )
+      end
+      let(:expected_html) do
+        '<figure><div class="embed">Embedded Object: something-666</div>' \
+          '<figcaption>Foo Bar</figcaption></figure>'
+      end
+      it { should eq expected_html }
+    end
   end
 
   describe '#element_classes' do

spec/article_json/elements/export/html/embed_spec.rb

@@ -0,0 +1,21 @@
+describe ArticleJSON::Export::HTML::Elements::Embed do
+  subject(:element) { described_class.new(source_element) }
+
+  let(:source_element) do
+    ArticleJSON::Elements::Embed.new(
+      embed_type: :something,
+      embed_id: 666,
+      caption: [ArticleJSON::Elements::Text.new(content: 'Foo Bar')],
+      tags: %w(test)
+    )
+  end
+
+  describe '#build' do
+    subject { element.build.to_html(save_with: 0) }
+    let(:expected_html) do
+      '<figure><div class="embed">Embedded Object: something-666</div>' \
+        '<figcaption>Foo Bar</figcaption></figure>'
+    end
+    it { should eq expected_html }
+  end
+end