allow title of special section to be hidden by setting untitled optio…

…n on section

CHANGELOG.adoc

@@ -20,6 +20,7 @@ Enhancements::
 * allow theme to control background color and border offset (only for background) for links (#1705)
 * don't show link URL next to link text when media is not screen and show-link-uri is unset
 * don't render index section if index is empty (i.e., there are no index entries)
+* allow title of special section to be hidden by setting "untitled" option on section
 * stabilize font paths in built-in themes by prefixing paths with GEM_FONTS_DIR (#1568)
 * assign page-layout attribute in running content so it can be used select background per layout (#1570)
 * reset numbering of footnotes in each chapter; add chapter xreftext to label of footnote reference that refers to previous chapter (#1639)

lib/asciidoctor/pdf/converter.rb

@@ -681,7 +681,7 @@ def convert_section sect, _opts = {}
           if sectname == 'part'
             layout_part_title sect, title, align: align, level: hlevel
           elsif chapterlike
-            layout_chapter_title sect, title, align: align, level: hlevel
+            layout_chapter_title sect, title, align: align, level: hlevel unless sect.special && (sect.option? 'untitled')
           else
             layout_general_heading sect, title, align: align, level: hlevel, outdent: true
           end

spec/section_spec.rb

@@ -713,6 +713,41 @@
     (expect appendix_text[:page_number]).to be 4
   end
 
+  it 'should not output section title for special section marked with untitled option' do
+    pdf = to_pdf <<~'EOS', pdf_theme: { heading_h2_font_color: 'AA0000' }, analyze: true
+    = Document Title
+    :doctype: book
+
+    [colophon%untitled]
+    = Hide Me
+
+    Colophon with no title.
+
+    = Part
+
+    == Chapter
+
+    content
+
+    [appendix]
+    = Details
+
+    We let you know.
+    EOS
+
+    colophon_page_text = pdf.find_text page_number: 2
+    (expect colophon_page_text).to have_size 1
+    (expect colophon_page_text[0][:string]).to eql 'Colophon with no title.'
+    chapter_texts = pdf.find_text font_color: 'AA0000'
+    (expect chapter_texts).to have_size 2
+    chapter_text = chapter_texts[0]
+    (expect chapter_text[:string]).to eql 'Chapter'
+    (expect chapter_text[:page_number]).to be 4
+    appendix_text = chapter_texts[1]
+    (expect appendix_text[:string]).to eql 'Appendix A: Details'
+    (expect appendix_text[:page_number]).to be 5
+  end
+
   it 'should not promote anonymous preface in book doctype to preface section if preface-title attribute is not set' do
     input = <<~'EOS'
     = Book Title