Fix inline paragraph block level replace bug (#131)

* Implement logic to replace the parent of an InlineParagraphBlock

This block handles logic where the start and end fields occur inside
the same paragraph. This works without issue unless the content being
injected (i.e. WordML or HTML) is not allowed inside a Paragraph.
When this occured an undefined method `next_element' for nil:NilClass
exception would be throw because a parent paragraph could not be found.

* Add integration test for InlineParagraphBlock parent replacement

* Remove unneeded ParagraphBlock inheirentance from ImageBlock

Inheiriting from the Block class is sufficent, and not as misleading.

* Implement test to exercise inline image insertion

This includes inline if and loop constructs.

lib/sablon/processor/document/blocks.rb

@@ -86,7 +86,7 @@ def self.encloses?(start_field, end_field)
         end
       end
 
-      class ImageBlock < ParagraphBlock
+      class ImageBlock < Block
         def self.encloses?(start_field, end_field)
           start_field.expression.start_with?('@')
         end
@@ -104,8 +104,8 @@ def replace(image)
               blip.attributes['embed'].value = image.local_rid if blip
               drawing_size = node.at_xpath('.//wp:extent')
 
-          # if image properties are defined, the size of the placeholder image
-          # should be replaced with the actual values
+              # if image properties are defined, the size of the placeholder
+              # image should be replaced with the actual values
               if image.width && image.height
                 drawing_size.attributes['cx'].value = image.width.to_s if drawing_size
                 drawing_size.attributes['cy'].value = image.height.to_s if drawing_size
@@ -126,6 +126,28 @@ def self.encloses?(start_field, end_field)
           super && parent(start_field) == parent(end_field)
         end
 
+        def process(env)
+          # Create a mock document structure so xpath queries will work
+          # correctly on block level content (i.e. searching for the first
+          # ancestor paragraph)
+          doc_node = Nokogiri::XML::Node.new('document', start_node.document)
+          doc_node.namespace = start_node.parent.namespace
+          p_node = Nokogiri::XML::Node.new('p', doc_node.document)
+          p_node.namespace = start_node.parent.namespace
+          p_node.children = Nokogiri::XML::NodeSet.new(p_node.document,
+                                                       body.map(&:dup))
+          doc_node.children = Nokogiri::XML::NodeSet.new(p_node.document,
+                                                         [p_node])
+          Processor::Document.process doc_node, env
+
+          if p_node.parent.nil?
+            replace_parent_node(doc_node.children)
+            []
+          else
+            p_node.children
+          end
+        end
+
         def remove_control_elements
           body.each(&:remove)
           start_field.remove
@@ -139,6 +161,16 @@ def start_node
         def end_node
           @end_node ||= end_field.start_node
         end
+
+        private
+
+        # A block level insertion has occurred which must replace the
+        # parent paragraph of the start node.
+        def replace_parent_node(content)
+          node = start_node.ancestors('.//w:p').first
+          content.each { |n| node.add_next_sibling n }
+          node.remove
+        end
       end
     end
   end

test/sablon_test.rb

@@ -105,7 +105,8 @@ def test_generate_document_from_template
       object: OpenStruct.new(true_method: true, false_method: false),
       success_content: '✓',
       fail_content: '✗',
-      content: 'Some Content'
+      content: 'Some Content',
+      block_content: Sablon.content(:html, '<p>HTML paragraph injected</p>')
     }
     #
     template.render_to_file @output_path, context
@@ -155,7 +156,7 @@ def test_generate_document_from_template
     darth = Sablon.content(:image, @image_fixtures.join('darth_vader.jpg'))
     #
     im_data = StringIO.new(IO.binread(@image_fixtures.join('clone.jpg')))
-    trooper = Sablon.content(:image, im_data, filename: 'clone.jpg', properties: {height: '8cm', width: '4cm'})
+    trooper = Sablon.content(:image, im_data, filename: 'clone.jpg', properties: {height: '1cm', width: '4cm'})
     #
     # with the following context setup all trooper should be reused and
     # only a single file added to media. R2D2 should get duplicated in the