def test_func
    html = 'sdafdf'
    css_border do
      html
    end
  end

  def css_border &block
    raise "Block missing." unless block_given?
    concat "Awesome", block.binding
    yield
    concat "Awesome2", block.binding
  end


and...

<% css_border do %>
test test
<% end %>

<br />

<%= test_func %>