[dropbox] fix name mangling by replacing lstrip with removeprefix

storages/backends/dropbox.py

@@ -33,6 +33,12 @@ class DropboxStorageException(Exception):
 DropBoxStorageException = DropboxStorageException
 
 
+def removeprefix(prefix, name):
+    if name.startswith(prefix):
+        name = name[len(prefix):]
+    return name
+
+
 class DropboxFile(File):
     def __init__(self, name, storage):
         self.name = name
@@ -172,7 +178,7 @@ def _save(self, name, content):
         content.close()
         # .save() validates the filename isn't absolute but Dropbox requires an absolute filename.
         # Work with the absolute name internally but strip it off before passing up-the-chain.
-        return name.lstrip(self.root_path)
+        return removeprefix(self.root_path, name).lstrip('/')
 
     def _chunked_upload(self, content, dest_path):
         upload_session = self.client.files_upload_session_start(

tests/test_dropbox.py

@@ -197,9 +197,11 @@ def test_jailed(self, *args):
     @mock.patch('dropbox.Dropbox.files_upload', return_value='foo')
     @mock.patch('dropbox.Dropbox.files_get_metadata', return_value=None)
     def test_saves(self, *args):
-        self.storage = dropbox.DropboxStorage('foo', root_path='/bar')
-        name = self.storage.save('xyz', File(io.BytesIO(b'abc'), 'def'))
-        self.assertEqual(name, 'xyz')
+        self.storage = dropbox.DropboxStorage('foo', root_path='/app.qoo.foo/')
+        for filename in ['xyz', 'quark']:
+            with self.subTest(filename=filename):
+                name = self.storage.save(filename, File(io.BytesIO(b'abc'), 'def'))
+                self.assertEqual(name, filename)
 
     def test_suspicious(self, *args):
         self.storage = dropbox.DropboxStorage('foo', root_path='/bar')