Opus/M4A-Cover-Embedding, cover.py-Tests und OCR-Tests

- tagger.py: embed_cover() unterstützt jetzt .opus (Vorbis-Comment
  METADATA_BLOCK_PICTURE) und .m4a (MP4Cover); imports ergänzt
- test_tagger.py: 2 neue Tests für Opus/M4A; minimale Audio-Fixtures
  als base64-Konstanten (176 B Opus, 856 B M4A)
- test_cover.py: TestPrepareCover (5 Tests) und TestCopyCovers (6 Tests)
  für prepare_cover() und copy_covers()
- test_ocr.py: 13 Tests für run_ocr(), _detect_and_fix_rotation()
  und ocr_images(); Tesseract via subprocess.run gemockt

144 Tests, 0 Fehler

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_cover.py

@@ -2,7 +2,18 @@
 
 from pathlib import Path
 
-from musiksammlung.cover import find_cover
+from PIL import Image
+
+from musiksammlung.cover import copy_covers, find_cover, prepare_cover
+
+
+def _make_image(path: Path, size: tuple[int, int] = (100, 100), mode: str = "RGB") -> Path:
+    img = Image.new(mode, size, color=(200, 100, 50))
+    fmt = "PNG" if path.suffix.lower() == ".png" else "JPEG"
+    if mode == "RGBA" and fmt == "JPEG":
+        img = img.convert("RGB")
+    img.save(str(path), fmt)
+    return path
 
 
 class TestFindCover:
@@ -41,3 +52,70 @@ class TestFindCover:
         (tmp_path / "cover.jpg").touch()
         (tmp_path / "back.jpg").touch()
         assert find_cover(tmp_path, "front") is None
+
+
+class TestPrepareCover:
+    def test_creates_jpeg_output(self, tmp_path: Path) -> None:
+        src = _make_image(tmp_path / "src.jpg")
+        dst = tmp_path / "out.jpg"
+        prepare_cover(src, dst)
+        assert dst.exists()
+        assert Image.open(dst).format == "JPEG"
+
+    def test_scales_down_large_image(self, tmp_path: Path) -> None:
+        src = _make_image(tmp_path / "src.jpg", size=(2000, 2000))
+        dst = tmp_path / "out.jpg"
+        prepare_cover(src, dst, max_size=1200)
+        assert max(Image.open(dst).size) <= 1200
+
+    def test_does_not_upscale_small_image(self, tmp_path: Path) -> None:
+        src = _make_image(tmp_path / "src.jpg", size=(300, 300))
+        dst = tmp_path / "out.jpg"
+        prepare_cover(src, dst, max_size=1200)
+        assert max(Image.open(dst).size) <= 300
+
+    def test_converts_rgba_to_rgb(self, tmp_path: Path) -> None:
+        src = tmp_path / "src.png"
+        Image.new("RGBA", (100, 100), (255, 0, 0, 128)).save(str(src), "PNG")
+        dst = tmp_path / "out.jpg"
+        prepare_cover(src, dst)
+        assert Image.open(dst).mode == "RGB"
+
+    def test_creates_parent_directory(self, tmp_path: Path) -> None:
+        src = _make_image(tmp_path / "src.jpg")
+        dst = tmp_path / "subdir" / "nested" / "out.jpg"
+        prepare_cover(src, dst)
+        assert dst.exists()
+
+
+class TestCopyCovers:
+    def test_copies_front_cover(self, tmp_path: Path) -> None:
+        src = _make_image(tmp_path / "src.jpg")
+        copy_covers(src, None, tmp_path)
+        assert (tmp_path / "frontcover.jpg").exists()
+
+    def test_copies_back_cover(self, tmp_path: Path) -> None:
+        src = _make_image(tmp_path / "src.jpg")
+        copy_covers(None, src, tmp_path)
+        assert (tmp_path / "backcover.jpg").exists()
+
+    def test_copies_both_covers(self, tmp_path: Path) -> None:
+        front = _make_image(tmp_path / "front.jpg")
+        back = _make_image(tmp_path / "back.jpg")
+        copy_covers(front, back, tmp_path)
+        assert (tmp_path / "frontcover.jpg").exists()
+        assert (tmp_path / "backcover.jpg").exists()
+
+    def test_skips_nonexistent_front(self, tmp_path: Path) -> None:
+        copy_covers(tmp_path / "nope.jpg", None, tmp_path)
+        assert not (tmp_path / "frontcover.jpg").exists()
+
+    def test_skips_nonexistent_back(self, tmp_path: Path) -> None:
+        copy_covers(None, tmp_path / "nope.jpg", tmp_path)
+        assert not (tmp_path / "backcover.jpg").exists()
+
+    def test_existing_frontcover_not_overwritten_when_no_source(self, tmp_path: Path) -> None:
+        existing = _make_image(tmp_path / "frontcover.jpg")
+        original_mtime = existing.stat().st_mtime
+        copy_covers(None, None, tmp_path)
+        assert (tmp_path / "frontcover.jpg").stat().st_mtime == original_mtime