diff --git a/src/documents/models.py b/src/documents/models.py
index b544f413d..d81343afa 100755
--- a/src/documents/models.py
+++ b/src/documents/models.py
@@ -221,7 +221,7 @@ class Document(models.Model):
         else:
             fname = "{:07}{}".format(self.pk, self.file_type)
             if self.storage_type == self.STORAGE_TYPE_GPG:
-                fname += ".gpg"
+                fname += ".gpg"  # pragma: no cover
 
         return os.path.join(
             settings.ORIGINALS_DIR,
diff --git a/src/documents/tests/test_sanity_check.py b/src/documents/tests/test_sanity_check.py
index 725e87617..0554cd7cd 100644
--- a/src/documents/tests/test_sanity_check.py
+++ b/src/documents/tests/test_sanity_check.py
@@ -2,6 +2,8 @@ import os
 import shutil
 from pathlib import Path
 
+import filelock
+from django.conf import settings
 from django.test import TestCase
 
 from documents.models import Document
@@ -13,9 +15,11 @@ class TestSanityCheck(DirectoriesMixin, TestCase):
 
     def make_test_data(self):
 
-        shutil.copy(os.path.join(os.path.dirname(__file__), "samples", "documents", "originals", "0000001.pdf"), os.path.join(self.dirs.originals_dir, "0000001.pdf"))
-        shutil.copy(os.path.join(os.path.dirname(__file__), "samples", "documents", "archive", "0000001.pdf"), os.path.join(self.dirs.archive_dir, "0000001.pdf"))
-        shutil.copy(os.path.join(os.path.dirname(__file__), "samples", "documents", "thumbnails", "0000001.png"), os.path.join(self.dirs.thumbnail_dir, "0000001.png"))
+        with filelock.FileLock(settings.MEDIA_LOCK):
+            # just make sure that the lockfile is present.
+            shutil.copy(os.path.join(os.path.dirname(__file__), "samples", "documents", "originals", "0000001.pdf"), os.path.join(self.dirs.originals_dir, "0000001.pdf"))
+            shutil.copy(os.path.join(os.path.dirname(__file__), "samples", "documents", "archive", "0000001.pdf"), os.path.join(self.dirs.archive_dir, "0000001.pdf"))
+            shutil.copy(os.path.join(os.path.dirname(__file__), "samples", "documents", "thumbnails", "0000001.png"), os.path.join(self.dirs.thumbnail_dir, "0000001.png"))
 
         return Document.objects.create(title="test", checksum="42995833e01aea9b3edee44bbfdd7ce1", archive_checksum="62acb0bcbfbcaa62ca6ad3668e4e404b", content="test", pk=1, filename="0000001.pdf", mime_type="application/pdf")
 
diff --git a/src/documents/tests/utils.py b/src/documents/tests/utils.py
index 7f9d50ed5..dfefc4061 100644
--- a/src/documents/tests/utils.py
+++ b/src/documents/tests/utils.py
@@ -34,7 +34,8 @@ def setup_directories():
         ARCHIVE_DIR=dirs.archive_dir,
         CONSUMPTION_DIR=dirs.consumption_dir,
         INDEX_DIR=dirs.index_dir,
-        MODEL_FILE=os.path.join(dirs.data_dir, "classification_model.pickle")
+        MODEL_FILE=os.path.join(dirs.data_dir, "classification_model.pickle"),
+        MEDIA_LOCK=os.path.join(dirs.media_dir, "media.lock")
 
     )
     dirs.settings_override.enable()
diff --git a/src/paperless_mail/mail.py b/src/paperless_mail/mail.py
index a82c34f15..3c200362d 100644
--- a/src/paperless_mail/mail.py
+++ b/src/paperless_mail/mail.py
@@ -26,7 +26,7 @@ class BaseMailAction:
         return {}
 
     def post_consume(self, M, message_uids, parameter):
-        pass
+        pass  # pragma: nocover
 
 
 class DeleteMailAction(BaseMailAction):
@@ -69,7 +69,7 @@ def get_rule_action(rule):
     elif rule.action == MailRule.ACTION_MARK_READ:
         return MarkReadMailAction()
     else:
-        raise ValueError("Unknown action.")
+        raise NotImplementedError("Unknown action.")  # pragma: nocover
 
 
 def make_criterias(rule):
@@ -95,7 +95,7 @@ def get_mailbox(server, port, security):
     elif security == MailAccount.IMAP_SECURITY_SSL:
         mailbox = MailBox(server, port)
     else:
-        raise ValueError("Unknown IMAP security")
+        raise NotImplementedError("Unknown IMAP security")  # pragma: nocover
     return mailbox
 
 
@@ -119,7 +119,7 @@ class MailAccountHandler(LoggingMixin):
             return os.path.splitext(os.path.basename(att.filename))[0]
 
         else:
-            raise ValueError("Unknown title selector.")
+            raise NotImplementedError("Unknown title selector.")  # pragma: nocover  # NOQA: E501
 
     def get_correspondent(self, message, rule):
         c_from = rule.assign_correspondent_from
@@ -141,7 +141,7 @@ class MailAccountHandler(LoggingMixin):
             return rule.assign_correspondent
 
         else:
-            raise ValueError("Unknwown correspondent selector")
+            raise NotImplementedError("Unknwown correspondent selector")  # pragma: nocover  # NOQA: E501
 
     def handle_mail_account(self, account):