Chore: Move unittest directory setup onto the shared fixture (#14172)

The unittest side of the suite built its temp directory tree with
tempfile.mkdtemp and a manually enabled override_settings, cleaned up only if
tearDown ran. That is now gone. DirectoriesMixin lives alongside the layout it
bridges and does nothing but hand the paperless_dirs fixture to TestCase
subclasses as self.dirs, so both halves of the suite get the same twelve
settings, the same directory shapes and cleanup owned by tmp_path.

The mixin moves to paperless_testing.dirs rather than staying in the documents
test utilities, because modules in paperless and paperless_mail import it
across the app boundary. The thirty-eight consuming modules change only their
import line; self.dirs.scratch_dir and its siblings keep working.

src/paperless_mail/tests/test_api.py

@@ -7,7 +7,6 @@ from guardian.shortcuts import assign_perm
 from rest_framework import status
 from rest_framework.test import APITestCase
 
-from documents.tests.utils import DirectoriesMixin
 from paperless_mail.models import MailAccount
 from paperless_mail.models import MailRule
 from paperless_mail.models import ProcessedMail
@@ -15,6 +14,7 @@ from paperless_mail.tests.factories import MailAccountFactory
 from paperless_mail.tests.factories import MailRuleFactory
 from paperless_mail.tests.factories import ProcessedMailFactory
 from paperless_mail.tests.test_mail import BogusMailBox
+from paperless_testing.dirs import DirectoriesMixin
 from paperless_testing.factories import CorrespondentFactory
 from paperless_testing.factories import DocumentTypeFactory
 from paperless_testing.factories import TagFactory

src/paperless_mail/tests/test_mail.py

@@ -28,7 +28,6 @@ from rest_framework.test import APITestCase
 
 from documents.models import Correspondent
 from documents.models import MatchingModel
-from documents.tests.utils import DirectoriesMixin
 from documents.tests.utils import FileSystemAssertsMixin
 from paperless_mail import tasks
 from paperless_mail.mail import MailAccountHandler
@@ -42,6 +41,7 @@ from paperless_mail.models import MailRule
 from paperless_mail.models import ProcessedMail
 from paperless_mail.tests.factories import MailAccountFactory
 from paperless_mail.tests.factories import MailRuleFactory
+from paperless_testing.dirs import DirectoriesMixin
 from paperless_testing.factories import CorrespondentFactory
 
 

src/paperless_mail/tests/test_mail_nfc.py

@@ -13,8 +13,6 @@ from unittest import mock
 
 import pytest
 
-from documents.tests.utils import remove_dirs
-from documents.tests.utils import setup_directories
 from paperless_mail.models import MailRule
 from paperless_mail.tests.factories import MailAccountFactory
 from paperless_mail.tests.test_mail import MessageBuilder
@@ -22,13 +20,6 @@ from paperless_mail.tests.test_mail import _AttachmentDef
 from paperless_mail.tests.test_mail import fake_magic_from_buffer
 
 
-@pytest.fixture()
-def directories(settings):
-    dirs = setup_directories()
-    yield dirs
-    remove_dirs(dirs)
-
-
 @pytest.fixture()
 def queue_consumption_tasks_mock():
     with mock.patch("paperless_mail.mail.queue_consumption_tasks") as m:
@@ -78,7 +69,7 @@ class TestMailNFCNormalization:
 
     def test_attachment_nfd_filename_normalized_to_nfc(
         self,
-        directories,
+        paperless_dirs,
         queue_consumption_tasks_mock,
         attachment_rule,
         mail_account_handler,
@@ -123,7 +114,7 @@ class TestMailNFCNormalization:
 
     def test_eml_subject_filename_nfc(
         self,
-        directories,
+        paperless_dirs,
         queue_consumption_tasks_mock,
         eml_rule,
         mail_account_handler,
@@ -156,7 +147,7 @@ class TestMailNFCNormalization:
 
     def test_already_nfc_attachment_filename_unchanged(
         self,
-        directories,
+        paperless_dirs,
         queue_consumption_tasks_mock,
         attachment_rule,
         mail_account_handler,