Move archive extraction from memory to stream (#965)

tests/download/test_archive_extraction.py

@@ -0,0 +1,78 @@
+from __future__ import annotations
+
+from pathlib import Path
+
+from shelfmark.download import archive as archive_mod
+
+
+class _FakeZipInfo:
+    filename = "book.epub"
+    flag_bits = 0
+
+    def is_dir(self) -> bool:
+        return False
+
+
+class _ChunkOnlyStream:
+    def __init__(self, content: bytes) -> None:
+        self._content = content
+        self._offset = 0
+        self.whole_read_called = False
+
+    def __enter__(self) -> _ChunkOnlyStream:
+        return self
+
+    def __exit__(self, *_args: object) -> None:
+        return None
+
+    def read(self, size: int = -1) -> bytes:
+        if size < 0:
+            self.whole_read_called = True
+            msg = "archive member was read into memory"
+            raise AssertionError(msg)
+
+        chunk = self._content[self._offset : self._offset + size]
+        self._offset += len(chunk)
+        return chunk
+
+
+class _FakeZipFile:
+    stream: _ChunkOnlyStream
+
+    def __init__(self, _path: Path, _mode: str) -> None:
+        self.stream = _ChunkOnlyStream(b"streamed archive content")
+
+    def __enter__(self) -> _FakeZipFile:
+        return self
+
+    def __exit__(self, *_args: object) -> None:
+        return None
+
+    def infolist(self) -> list[_FakeZipInfo]:
+        return [_FakeZipInfo()]
+
+    def testzip(self) -> None:
+        return None
+
+    def open(self, _info: _FakeZipInfo) -> _ChunkOnlyStream:
+        return self.stream
+
+
+def test_extract_archive_raw_streams_members_without_whole_read(
+    tmp_path: Path, monkeypatch
+) -> None:
+    fake_archives: list[_FakeZipFile] = []
+
+    def fake_zip_file(path: Path, mode: str) -> _FakeZipFile:
+        archive = _FakeZipFile(path, mode)
+        fake_archives.append(archive)
+        return archive
+
+    monkeypatch.setattr(archive_mod.zipfile, "ZipFile", fake_zip_file)
+
+    extracted_files, warnings = archive_mod.extract_archive_raw(tmp_path / "book.zip", tmp_path)
+
+    assert warnings == []
+    assert [path.name for path in extracted_files] == ["book.epub"]
+    assert extracted_files[0].read_bytes() == b"streamed archive content"
+    assert fake_archives[0].stream.whole_read_called is False