diff --git a/mayan/apps/sources/tests/mocks.py b/mayan/apps/sources/tests/mocks.py
index b80fb664e0..775b9b4b84 100644
--- a/mayan/apps/sources/tests/mocks.py
+++ b/mayan/apps/sources/tests/mocks.py
@@ -216,3 +216,32 @@ class MockIMAPServer(object):
             ]
 
             return ('OK', [' '.join(message_sequences)])
+
+
+class MockPOP3Mailbox(object):
+    def dele(self, which):
+        return
+
+    def getwelcome(self):
+        return
+
+    def list(self, which=None):
+        return (None, ['1 test'])
+
+    def user(self, user):
+        return
+
+    def pass_(self, pswd):
+        return
+
+    def quit(self):
+        return
+
+    def retr(self, which=None):
+        return (
+            1, [TEST_EMAIL_BASE64_FILENAME]
+        )
+
+
+class MockStagingFolder(object):
+    """Mock of a StagingFolder model"""
diff --git a/mayan/apps/sources/tests/test_classes.py b/mayan/apps/sources/tests/test_classes.py
index 76f70e1935..222f2f4538 100644
--- a/mayan/apps/sources/tests/test_classes.py
+++ b/mayan/apps/sources/tests/test_classes.py
@@ -9,6 +9,8 @@ from mayan.apps.storage.utils import mkdtemp
 
 from ..classes import StagingFile
 
+from .mocks import MockStagingFolder
+
 
 class StagingFileTestCase(BaseTestCase):
     def test_unicode_staging_file(self):
@@ -17,9 +19,6 @@ class StagingFileTestCase(BaseTestCase):
 
         filename = os.path.basename(TEST_NON_ASCII_DOCUMENT_PATH)
 
-        class MockStagingFolder(object):
-            self.folder_path = temporary_directory
-
         staging_file_1 = StagingFile(
             staging_folder=MockStagingFolder(),
             filename=filename
diff --git a/mayan/apps/sources/tests/test_models.py b/mayan/apps/sources/tests/test_models.py
index b0fa2561f1..b1e53193d2 100644
--- a/mayan/apps/sources/tests/test_models.py
+++ b/mayan/apps/sources/tests/test_models.py
@@ -25,9 +25,6 @@ from ..literals import SOURCE_UNCOMPRESS_CHOICE_Y
 from ..models.email_sources import EmailBaseModel, IMAPEmail, POP3Email
 from ..models.watch_folder_sources import WatchFolderSource
 
-from .mocks import MockIMAPServer
-
-
 from .literals import (
     TEST_EMAIL_ATTACHMENT_AND_INLINE, TEST_EMAIL_BASE64_FILENAME,
     TEST_EMAIL_BASE64_FILENAME_FROM, TEST_EMAIL_BASE64_FILENAME_SUBJECT,
@@ -36,7 +33,7 @@ from .literals import (
     TEST_WATCHFOLDER_SUBFOLDER
 )
 from .mixins import SourceTestMixin
-from .mocks import MockIMAPServer
+from .mocks import MockIMAPServer, MockPOP3Mailbox
 
 
 class CompressedUploadsTestCase(SourceTestMixin, GenericDocumentTestCase):
@@ -284,33 +281,9 @@ class IMAPSourceTestCase(GenericDocumentTestCase):
 class POP3SourceTestCase(GenericDocumentTestCase):
     auto_upload_document = False
 
-    class MockMailbox(object):
-        def dele(self, which):
-            return
-
-        def getwelcome(self):
-            return
-
-        def list(self, which=None):
-            return (None, ['1 test'])
-
-        def user(self, user):
-            return
-
-        def pass_(self, pswd):
-            return
-
-        def quit(self):
-            return
-
-        def retr(self, which=None):
-            return (
-                1, [TEST_EMAIL_BASE64_FILENAME]
-            )
-
     @mock.patch('poplib.POP3_SSL', autospec=True)
     def test_download_document(self, mock_poplib):
-        mock_poplib.return_value = POP3SourceTestCase.MockMailbox()
+        mock_poplib.return_value = MockPOP3Mailbox()
         self.source = POP3Email.objects.create(
             document_type=self.test_document_type, label='', host='',
             password='', username=''