v2.1.0 breaking changes

[Kizr]

The Issue

After upgrading to v2.1.0, we noticed that all of our mailer specs started failing. After investigating I have tracked the issue to the removal of the headers hash from the call to ActionMailer::Base#mail within the Mail::Notify::Mailer#view_mail method.

mail-notify/lib/mail/notify/mailer.rb

Line 85 in f4c92ac

body = mail.body.raw_source

I found a comment from @mec fairly questioning the usefulness of passing headers through to the ActionMailer::Base#mail method, however I think some of the headers are still useful, despite not being passed through to Notify.

Our application does not make use of mailer templates for all of our mailers, and we instead rely on yaml files to define our content. In the ActionMailer::Base#mail method, one of the accepted headers is body, when a body header is specified the method will utilise the value passed through instead of looking for a template - in our case a template does not exist and therefore causes an error when upgrading to the latest version of this gem.

Also of note are the template_path and template_name headers which may also result in a similar error if other applications utilise these headers for non-standard template paths.

Potential solutions

I agree with the general line of thought that limiting headers makes sense, so I'm not proposing that we pull through the entire headers hash again, however I do think the inclusion of body, template_path and template_name headers would be sensible given the intent of this method is to set the body in the personalisation so that it can be sent through to the Notify API and these headers specifically aid in finding the content for the message body.