Only set Auto-Submitted header once

The emails on push feature reuses the same email object, to avoid the expensive work of generating the email body. This interceptor would previously set multiple values for the same header, as that's the mail gem's default behaviour when called with the same header more than once. We don't want to change the emails on push service (although it's the only place where this happens), but fixing the interceptor is just as sensible anyway.

Only set Auto-Submitted header once
eddc9e41 · Sean McGivern · 9a58468b · eddc9e41 · eddc9e41 · eddc9e41
Commit eddc9e41 authored Oct 30, 2017 by Sean McGivern
3 changed files
--- a/changelogs/unreleased/39593-emails-on-push-are-sent-to-only-the-first-recipient-when-using-aws-ses.yml
+++ b/changelogs/unreleased/39593-emails-on-push-are-sent-to-only-the-first-recipient-when-using-aws-ses.yml
+---
+title: Only set Auto-Submitted header once for emails on push
+merge_request:
+author:
+type: fixed
--- a/lib/additional_email_headers_interceptor.rb
+++ b/lib/additional_email_headers_interceptor.rb
 class AdditionalEmailHeadersInterceptor
  def self.delivering_email(message)
-    message.headers(
-      'Auto-Submitted' => 'auto-generated',
-      'X-Auto-Response-Suppress' => 'All'
-    )
+    message.header['Auto-Submitted'] ||= 'auto-generated'
+    message.header['X-Auto-Response-Suppress'] ||= 'All'
  end
 end
--- a/spec/lib/additional_email_headers_interceptor_spec.rb
+++ b/spec/lib/additional_email_headers_interceptor_spec.rb
 require 'spec_helper'

 describe AdditionalEmailHeadersInterceptor do
-  it 'adds Auto-Submitted header' do
-    mail = ActionMailer::Base.mail(to: 'test@mail.com', from: 'info@mail.com', body: 'hello').deliver
+  let(:mail) do
+    ActionMailer::Base.mail(to: 'test@mail.com', from: 'info@mail.com', body: 'hello')
+  end
+
+  before do
+    mail.deliver_now
+  end

+  it 'adds Auto-Submitted header' do
    expect(mail.header['To'].value).to eq('test@mail.com')
    expect(mail.header['From'].value).to eq('info@mail.com')
    expect(mail.header['Auto-Submitted'].value).to eq('auto-generated')
    expect(mail.header['X-Auto-Response-Suppress'].value).to eq('All')
  end
+
+  context 'when the same mail object is sent twice' do
+    before do
+      mail.deliver_now
+    end
+
+    it 'does not add the Auto-Submitted header twice' do
+      expect(mail.header['Auto-Submitted'].value).to eq('auto-generated')
+      expect(mail.header['X-Auto-Response-Suppress'].value).to eq('All')
+    end
+  end
 end