test-backend: Raise zerver/views/test_upload.py test coverage to 100%.

tools/test-backend

@@ -89,8 +89,6 @@ not_yet_fully_covered = {
     'zerver/views/auth.py',
     'zerver/views/home.py',
     'zerver/views/registration.py',
-    # This one has 1 line that isn't covered in Python 3
-    'zerver/views/upload.py',
     # Getting this to 100% is a major project goal.
     'zproject/backends.py',
 }

zerver/tests/test_upload.py

@@ -8,7 +8,11 @@ from zerver.lib.avatar import avatar_url
 from zerver.lib.bugdown import url_filename
 from zerver.lib.realm_icon import realm_icon_url
 from zerver.lib.test_classes import ZulipTestCase, UploadSerializeMixin
-from zerver.lib.test_helpers import avatar_disk_path, get_test_image_file
+from zerver.lib.test_helpers import (
+    avatar_disk_path,
+    get_test_image_file,
+    POSTRequestMock,
+)
 from zerver.lib.test_runner import slow
 from zerver.lib.upload import sanitize_name, S3UploadBackend, \
     upload_message_image, delete_message_image, LocalUploadBackend
@@ -17,6 +21,8 @@ from zerver.models import Attachment, Recipient, get_user_profile_by_email, \
     get_old_unclaimed_attachments, Message, UserProfile, Realm, get_realm
 from zerver.lib.actions import do_delete_old_unclaimed_attachments
 
+from zerver.views.upload import upload_file_backend
+
 import ujson
 from six.moves import urllib
 from PIL import Image
@@ -77,6 +83,44 @@ class FileUploadTest(UploadSerializeMixin, ZulipTestCase):
         self.login("hamlet@zulip.com")
         self.assert_url_serves_contents_of_file(uri, b"zulip!")
 
+    def test_filename_encoding(self):
+        # type: () -> None
+        """
+        In Python 2, we need to encode unicode filenames (which converts them to
+        str) before they can be rendered correctly.  However, in Python 3, the
+        separate unicode type does not exist, and we don't need to perform this
+        encoding.  This test ensures that we handle filename encodings properly,
+        and does so in a way that preserves 100% test coverage for Python 3.
+        """
+
+        user_profile = get_user_profile_by_email('hamlet@zulip.com')
+
+        mock_file = mock.Mock()
+        mock_file._get_size = mock.Mock(return_value=1024)
+
+        mock_files = mock.Mock()
+        mock_files.__len__ = mock.Mock(return_value=1)
+        mock_files.values = mock.Mock(return_value=[mock_file])
+
+        mock_request = mock.Mock()
+        mock_request.FILES = mock_files
+
+        # str filenames should not be encoded.
+        mock_filename = mock.Mock(spec=str)
+        mock_file.name = mock_filename
+        with mock.patch('zerver.views.upload.upload_message_image_from_request'):
+            result = upload_file_backend(mock_request, user_profile)
+        self.assert_json_success(result)
+        mock_filename.encode.assert_not_called()
+
+        # Non-str filenames should be encoded.
+        mock_filename = mock.Mock(spec=None) # None is not str
+        mock_file.name = mock_filename
+        with mock.patch('zerver.views.upload.upload_message_image_from_request'):
+            result = upload_file_backend(mock_request, user_profile)
+        self.assert_json_success(result)
+        mock_filename.encode.assert_called_once_with('ascii')
+
     def test_file_too_big_failure(self):
         # type: () -> None
         """