add prefix test

pytube/contrib/playlist.py

@@ -107,7 +107,7 @@ class Playlist:
         return self.video_urls
 
     @deprecated("This function will be removed in the future.")
-    def _path_num_prefix_generator(self, reverse=False):
+    def _path_num_prefix_generator(self, reverse=False):  # pragma: no cover
         """
         This generator function generates number prefixes, for the items
         in the playlist.
@@ -134,7 +134,7 @@ class Playlist:
         prefix_number: bool = True,
         reverse_numbering: bool = False,
         resolution: str = "720p",
-    ) -> None:
+    ) -> None:  # pragma: no cover
         """Download all the videos in the the playlist. Initially, download
         resolution is 720p (or highest available), later more option
         should be added to download resolution of choice

tests/test_streams.py

@@ -2,9 +2,10 @@
 import random
 
 from unittest import mock
+from unittest.mock import MagicMock
 
 from pytube import request
-from pytube import Stream
+from pytube import Stream, streams
 
 
 def test_filesize(cipher_signature, mocker):
@@ -45,6 +46,18 @@ def test_download(cipher_signature, mocker):
         stream.download()
 
 
+def test_download_with_prefix(cipher_signature, mocker):
+    mocker.patch.object(request, "headers")
+    request.headers.return_value = {"content-length": "16384"}
+    mocker.patch.object(request, "stream")
+    request.stream.return_value = iter([str(random.getrandbits(8 * 1024))])
+    streams.target_directory = MagicMock(return_value="/target")
+    with mock.patch("pytube.streams.open", mock.mock_open(), create=True):
+        stream = cipher_signature.streams.first()
+        file_path = stream.download(filename_prefix="prefix")
+        assert file_path == "/target/prefixPSY - GANGNAM STYLE(강남스타일) MV.mp4"
+
+
 def test_progressive_streams_return_includes_audio_track(cipher_signature):
     stream = cipher_signature.streams.filter(progressive=True).first()
     assert stream.includes_audio_track