Given a Rakefile with RDoc::Task configured for files, or using .document, it would be nice to generate a coverage report with the project file structure already known.

For example:

# Rakefile
require 'rdoc/task'

RDoc::Task.new do |rdoc|
  rdoc.rdoc_files.include("lib/foo.rb", "lib/foo/bar.rb")
end

We could then do something like:

rake rdoc --coverage

To generate the coverage report, given the known files and other configuration from the task.

This way generating a report for a project is much simpler then adding all project files to the coverage report command (rdoc -C ...)