Don't die when an attachment is missing a title

lib/govspeak.rb

@@ -203,7 +203,8 @@ def insert_strong_inside_p(body, parser=Govspeak::Document)
       attachment = AttachmentPresenter.new(attachment)
       span_id = attachment.id ? %{ id="attachment_#{attachment.id}"} : ""
       # new lines inside our title cause problems with govspeak rendering as this is expected to be on one line.
-      link = attachment.link(attachment.title.tr("\n", " "), attachment.url)
+      title = (attachment.title || "").tr("\n", " ")
+      link = attachment.link(title, attachment.url)
       attributes = attachment.attachment_attributes.empty? ? "" : " (#{attachment.attachment_attributes})"
       %{<span#{span_id} class="attachment-inline">#{link}#{attributes}</span>}
     end
@@ -212,7 +213,8 @@ def insert_strong_inside_p(body, parser=Govspeak::Document)
       attachment = attachments.detect { |a| a[:content_id].match(content_id) }
       next "" unless attachment
       attachment = AttachmentPresenter.new(attachment)
-      render_image(attachment.url, attachment.title.tr("\n", " "), nil, attachment.id)
+      title = (attachment.title || "").tr("\n", " ")
+      render_image(attachment.url, title, nil, attachment.id)
     end
 
     # As of version 1.12.0 of Kramdown the block elements (div & figcaption)

test/govspeak_attachments_image_test.rb

@@ -56,6 +56,14 @@ def compress_html(html)
     assert_match(%r{<img.*alt="My Title"}, rendered)
   end
 
+  test "can render a nil image title" do
+    rendered = render_govspeak(
+      "[embed:attachments:image:1fe8]",
+      [build_attachment(id: nil, title: nil, content_id: "1fe8")]
+    )
+    assert_match(%r{<img.*alt=""}, rendered)
+  end
+
   test "a full image attachment rendering looks correct" do
     rendered = render_govspeak(
       "[embed:attachments:image:1fe8]",

test/govspeak_attachments_inline_test.rb

@@ -44,6 +44,14 @@ def render_govspeak(govspeak, attachments = [])
     assert_match(%r{<a href="http://a.b/f.pdf">My Pdf</a>}, rendered)
   end
 
+  test "renders with a nil title" do
+    rendered = render_govspeak(
+      "[embed:attachments:inline:1fe8]",
+      [build_attachment(content_id: "1fe8", url: "http://a.b/f.pdf", title: nil)]
+    )
+    assert_match(%r{<a href="http://a.b/f.pdf"></a>}, rendered)
+  end
+
   test "renders on a single line" do
     rendered = render_govspeak(
       "[embed:attachments:inline:2bc1]",