ActionView::OutputBuffer to_s should return a real String

Recently when debugging an issue rendering an email, I ran across some unexpected behavior.

To help us in our tests when rendering an email we use this:

def render(template, local_assigns={})
view = ActionView::Base.new(["features/fixtures"]) view.render :file => template, :locals => local_assigns end

We would use this rendered output to create an email, but whenever we pull parts of the email out, like the body, it returns the part as a ActionView::OutputBuffer.

Even calling to_s on the body didn't help and after looking into it, it's obvious why: ActiveSupport::SafeBuffer, which ActionView::OutputBuffer inherits, returns self when calling to_s. I would expect to_s to at least attempt to return a string, maybe something like 'String.new self'.

Is there a reason for this behavior?

For Example:

This fails:
# this is equivalent to what we get when extracting emails out of our rendered template as described in the problem above a = ActionView::OutputBuffer.new "foo@example.com" Mail:Address.new a

This succeeds:
Mail:Address.new "foo@example.com"

API Reference for ActiveSupport::SafeBuffer
http://api.rubyonrails.org/classes/ActiveSupport/SafeBuffer.html#me...