improve mailer generator and add tests

Added third commit. This is how the generated mailer now looks like:

script/generate mailer notifier reset_password

In @app/models/notifier.rb@:

class Notifier < ActionMailer::Base
  
  # change to your domain name
  default_url_options[:host] = 'example.com'

  def reset_password(sent_at = Time.now)
    subject    'Notifier#reset_password'
    recipients ''
    from       ''
    sent_on    sent_at
    
    body       :greeting => 'Hi,'
  end

end

Got the third too, thanks!

http://github.com/rails/rails/co...

Question, how did you diff those patches? It included your name and email at the top which is really nice.

Can you doc the process under Ticket Guidelines Authorship.

git format-patch HEAD~3

I can't edit Ticket Guidelines, only core team can.

Great changes overall. However, I did notice one small potential issue. I don't think the default_url_options[:host] call should be placed in the mailer. This seems to promote setting the host in each mailer, but the host is likely to be the same in most cases. Also, default_url_options is a mattr_accessor so the settings in each mailer will overwrite each other, which is likely to be confusing for the developer.

It seems more useful to use something like the following in the application's configuration:

config.action_mailer.default_url_options = { :host => 'myhost.com' }

Well, I generally agree. We only have to update docs for ActionMailer and we can remove `default_url_options` from generator.

Please take a look at #32. I created a patch which updates the documentation and removes the default_url_options call from the generator.