Mailing: Add support for a from field

Add support to the mailing profiles for specifying a "from"
address. Closes GitLab issue #522.

This commit adds a new backend class property "class_fields"
which differs from the normal "fields" property. The "class_fields"
property specifies which of the backend fields will be used to
initialize a backend's driver class. This is to avoid passing
fields that the driver doesn't expect and getting an error.

When sending emails, the "send" method will attempt to get
a "from" key from the backend data and use that when sending
emails. If no "from" key is found a None is passes. Django's
behavior in this situation dictates that the "from" value will
then be taken from the DEFAULT_FROM_EMAIL setting.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/mailer/tests/test_models.py

@@ -5,8 +5,9 @@ from django.core import mail
 from mayan.apps.documents.tests.test_models import GenericDocumentTestCase
 
 from .literals import (
-    TEST_BODY_HTML, TEST_EMAIL_ADDRESS, TEST_RECIPIENTS_MULTIPLE_COMMA,
-    TEST_RECIPIENTS_MULTIPLE_COMMA_RESULT, TEST_RECIPIENTS_MULTIPLE_SEMICOLON,
+    TEST_BODY_HTML, TEST_EMAIL_ADDRESS, TEST_EMAIL_FROM_ADDRESS,
+    TEST_RECIPIENTS_MULTIPLE_COMMA, TEST_RECIPIENTS_MULTIPLE_COMMA_RESULT,
+    TEST_RECIPIENTS_MULTIPLE_SEMICOLON,
     TEST_RECIPIENTS_MULTIPLE_SEMICOLON_RESULT, TEST_RECIPIENTS_MULTIPLE_MIXED,
     TEST_RECIPIENTS_MULTIPLE_MIXED_RESULT,
 )
@@ -19,6 +20,7 @@ class ModelTestCase(MailerTestMixin, GenericDocumentTestCase):
         self.user_mailer.send(to=TEST_EMAIL_ADDRESS)
 
         self.assertEqual(len(mail.outbox), 1)
+        self.assertEqual(mail.outbox[0].from_email, TEST_EMAIL_FROM_ADDRESS)
         self.assertEqual(mail.outbox[0].to, [TEST_EMAIL_ADDRESS])
 
     def test_send_simple_with_html(self):
@@ -26,6 +28,7 @@ class ModelTestCase(MailerTestMixin, GenericDocumentTestCase):
         self.user_mailer.send(to=TEST_EMAIL_ADDRESS, body=TEST_BODY_HTML)
 
         self.assertEqual(len(mail.outbox), 1)
+        self.assertEqual(mail.outbox[0].from_email, TEST_EMAIL_FROM_ADDRESS)
         self.assertEqual(mail.outbox[0].to, [TEST_EMAIL_ADDRESS])
         self.assertEqual(mail.outbox[0].alternatives[0][0], TEST_BODY_HTML)
 
@@ -36,6 +39,7 @@ class ModelTestCase(MailerTestMixin, GenericDocumentTestCase):
         )
 
         self.assertEqual(len(mail.outbox), 1)
+        self.assertEqual(mail.outbox[0].from_email, TEST_EMAIL_FROM_ADDRESS)
         self.assertEqual(mail.outbox[0].to, [TEST_EMAIL_ADDRESS])
         with self.document.open() as file_object:
             self.assertEqual(
@@ -50,6 +54,7 @@ class ModelTestCase(MailerTestMixin, GenericDocumentTestCase):
         self.user_mailer.send(to=TEST_RECIPIENTS_MULTIPLE_COMMA)
 
         self.assertEqual(len(mail.outbox), 1)
+        self.assertEqual(mail.outbox[0].from_email, TEST_EMAIL_FROM_ADDRESS)
         self.assertEqual(
             mail.outbox[0].to, TEST_RECIPIENTS_MULTIPLE_COMMA_RESULT
         )
@@ -59,6 +64,7 @@ class ModelTestCase(MailerTestMixin, GenericDocumentTestCase):
         self.user_mailer.send(to=TEST_RECIPIENTS_MULTIPLE_SEMICOLON)
 
         self.assertEqual(len(mail.outbox), 1)
+        self.assertEqual(mail.outbox[0].from_email, TEST_EMAIL_FROM_ADDRESS)
         self.assertEqual(
             mail.outbox[0].to, TEST_RECIPIENTS_MULTIPLE_SEMICOLON_RESULT
         )
@@ -68,6 +74,7 @@ class ModelTestCase(MailerTestMixin, GenericDocumentTestCase):
         self.user_mailer.send(to=TEST_RECIPIENTS_MULTIPLE_MIXED)
 
         self.assertEqual(len(mail.outbox), 1)
+        self.assertEqual(mail.outbox[0].from_email, TEST_EMAIL_FROM_ADDRESS)
         self.assertEqual(
             mail.outbox[0].to, TEST_RECIPIENTS_MULTIPLE_MIXED_RESULT
         )