feat(twitter_threads): download_media.py — stdlib urllib + idempotent + typed per-kind naming

media_names_for_post derives <post_id>_<kind><index>.<ext> (img/vid/gif, per-kind counters) from media_urls; download_media(thread, output_dir) -> Result[list[Path]] downloads via stdlib urlopen, idempotent skip when target exists with size>0, URLError -> Result.err(HttpError). Authorized HTTP-boundary mock tests. TDD: red(no module) -> green(6 media + 16 regression pass).

tests/test_twitter_threads_media.py

@@ -0,0 +1,82 @@
+"""Tests for scripts.twitter_threads.download_media: naming and HTTP download contract."""
+from __future__ import annotations
+
+from pathlib import Path
+from unittest.mock import patch, MagicMock
+from urllib.error import URLError
+
+import pytest
+
+from scripts.twitter_threads.error_types import PostMetrics, PostData, ThreadData
+from scripts.twitter_threads.download_media import media_names_for_post, download_media
+
+
+class _FakeResp:
+ def __init__(self, data: bytes) -> None:
+  self._data = data
+ def read(self) -> bytes:
+  return self._data
+ def __enter__(self) -> "_FakeResp":
+  return self
+ def __exit__(self, *a: object) -> bool:
+  return False
+
+
+def _post(post_id: str, media_urls: tuple[str, ...]) -> PostData:
+ metrics = PostMetrics(reply_count=0, repost_count=0, like_count=0, view_count=None)
+ return PostData(post_id=post_id, author="Tim", handle="NOTimothyLottes", text="t", timestamp="2024-02-01T00:00:00Z", media_urls=media_urls, reply_to_id=None, quote_of_id=None, metrics=metrics)
+
+
+def test_media_names_for_post() -> None:
+ post = _post("123", ("https://pbs.twimg.com/media/A?format=jpg&name=large", "https://pbs.twimg.com/media/B?format=png&name=large"))
+ assert media_names_for_post(post) == ["123_img1.jpg", "123_img2.png"]
+
+
+def test_media_names_video() -> None:
+ post = _post("123", ("https://video.twimg.com/ext_tw_video/1/pu/vid/1280x720/1234567890.mp4",))
+ assert media_names_for_post(post) == ["123_vid1.mp4"]
+
+
+def test_download_naming(tmp_path: Path) -> None:
+ post = _post("123", ("https://pbs.twimg.com/media/A?format=jpg&name=large", "https://pbs.twimg.com/media/B?format=png&name=large"))
+ thread = ThreadData(root_post_id="123", posts=(post,), source_url="https://x.com/x/x/123")
+ with patch("scripts.twitter_threads.download_media.urlopen", return_value=_FakeResp(b"bytes")):
+  result = download_media(thread, tmp_path)
+ assert result.is_ok
+ assert (tmp_path / "123_img1.jpg").exists()
+ assert (tmp_path / "123_img2.png").exists()
+ assert result.data is not None
+ names = [p.name for p in result.data]
+ assert "123_img1.jpg" in names
+ assert "123_img2.png" in names
+
+
+def test_download_video_naming(tmp_path: Path) -> None:
+ post = _post("123", ("https://video.twimg.com/ext_tw_video/1/pu/vid/1280x720/1234567890.mp4",))
+ thread = ThreadData(root_post_id="123", posts=(post,), source_url="https://x.com/x/x/123")
+ with patch("scripts.twitter_threads.download_media.urlopen", return_value=_FakeResp(b"vid")):
+  result = download_media(thread, tmp_path)
+ assert (tmp_path / "123_vid1.mp4").exists()
+
+
+def test_download_idempotent(tmp_path: Path) -> None:
+ post = _post("123", ("https://pbs.twimg.com/media/A?format=jpg&name=large",))
+ thread = ThreadData(root_post_id="123", posts=(post,), source_url="https://x.com/x/x/123")
+ name = media_names_for_post(post)[0]
+ (tmp_path / name).write_bytes(b"already")
+ mock_urlopen = MagicMock()
+ with patch("scripts.twitter_threads.download_media.urlopen", mock_urlopen):
+  result = download_media(thread, tmp_path)
+ assert result.is_ok
+ mock_urlopen.assert_not_called()
+ assert (tmp_path / name).read_bytes() == b"already"
+
+
+def test_download_http_error(tmp_path: Path) -> None:
+ post = _post("123", ("https://pbs.twimg.com/media/A?format=jpg&name=large",))
+ thread = ThreadData(root_post_id="123", posts=(post,), source_url="https://x.com/x/x/123")
+ with patch("scripts.twitter_threads.download_media.urlopen", side_effect=URLError("boom")):
+  result = download_media(thread, tmp_path)
+ assert result.is_ok is False
+ assert result.error is not None
+ assert result.error.kind == "HttpError"