Fix section comments with the prism parser (#1639)

The section expects a non-formatted comment.
Closes #1638

Can be simplified once the ripper parser is removed. It currently passes
the comment text as is and transforms it in the section class itself.
The prism parser now does it outside of that class.

Author: Earlopain

lib/rdoc/code_object/context/section.rb

@@ -106,6 +106,9 @@ def legacy_aref
   #
   #   # :section: The title
   #   # The body
+  #
+  #--
+  # TODO Remove when the ripper parser has been removed
 
   def extract_comment(comment)
     case comment

lib/rdoc/parser/prism_ruby.rb

@@ -473,15 +473,28 @@ def parse_comment_text_to_directives(comment_text, start_line) # :nodoc:
     comment.line = start_line
     markup, = directives['markup']
     comment.format = markup&.downcase || @markup
-    if (section, = directives['section'])
+    if (section, directive_line = directives['section'])
       # If comment has :section:, it is not a documentable comment for a code object
-      @container.set_current_section(section, comment.dup)
+      comment.text = extract_section_comment(comment_text, directive_line - start_line)
+      @container.set_current_section(section, comment)
       return
     end
     @preprocess.run_post_processes(comment, @container)
     [comment, directives]
   end
 
+  # Extracts the comment for this section from the normalized comment block.
+  # Removes all lines before the line that contains :section:
+  # If the comment also ends with the same content, remove it as well
+
+  def extract_section_comment(comment_text, prefix_line_count) # :nodoc:
+    prefix = comment_text.lines[0...prefix_line_count].join
+    comment_text.delete_prefix!(prefix)
+    # Comment is already normalized and doesn't end with a newline
+    comment_text.delete_suffix!(prefix.chomp)
+    comment_text
+  end
+
   def slice_tokens(start_pos, end_pos) # :nodoc:
     start_index = @tokens.bsearch_index { |t| ([t.line_no, t.char_no] <=> start_pos) >= 0 }
     end_index = @tokens.bsearch_index { |t| ([t.line_no, t.char_no] <=> end_pos) >= 0 }

test/rdoc/parser/prism_ruby_test.rb

@@ -36,6 +36,41 @@ def test_look_for_directives_in_section
     assert_equal 'new section', section.title
   end
 
+  def test_section_with_divider
+    util_parser <<~RUBY
+      # DIVIDER
+      # :section: section 1
+      # foo
+      # DIVIDER
+
+      # DIVIDER 1
+      # DIVIDER 2
+      # :section: section 2
+      # foo
+      # DIVIDER 1
+      # DIVIDER 2
+
+      # DIVIDER TOP ONLY
+      # :section: section 3
+      # foo
+
+      # DIVIDER TOP ONLY
+      # :section: section 4
+    RUBY
+
+    section = @top_level.sections_hash['section 1']
+    assert_equal "\n<p>foo</p>\n", section.description
+
+    section = @top_level.sections_hash['section 2']
+    assert_equal "\n<p>foo</p>\n", section.description
+
+    section = @top_level.sections_hash['section 3']
+    assert_equal "\n<p>foo</p>\n", section.description
+
+    section = @top_level.sections_hash['section 4']
+    assert_equal '', section.description
+  end
+
   def test_look_for_directives_in_commented
     util_parser <<~RUBY
       # how to make a section: