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_ocr.py

@@ -0,0 +1,191 @@
+"""Tests für OCR-Funktionen (subprocess via Mock)."""
+
+from __future__ import annotations
+
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+from PIL import Image
+
+from musiksammlung.ocr import _detect_and_fix_rotation, ocr_images, run_ocr
+
+
+def _fake_run(stdout: str = "", returncode: int = 0) -> MagicMock:
+    """Erstellt ein Mock-subprocess.CompletedProcess."""
+    result = MagicMock()
+    result.returncode = returncode
+    result.stdout = stdout
+    result.stderr = ""
+    return result
+
+
+def _make_image(path: Path, size: tuple[int, int] = (100, 100)) -> Path:
+    Image.new("RGB", size, color=(200, 100, 50)).save(str(path), "JPEG")
+    return path
+
+
+# ---------------------------------------------------------------------------
+# run_ocr
+# ---------------------------------------------------------------------------
+
+
+class TestRunOcr:
+    def test_returns_stdout_on_success(self, tmp_path: Path) -> None:
+        img = _make_image(tmp_path / "test.jpg")
+        with patch("musiksammlung.ocr.subprocess.run", return_value=_fake_run("Trackliste\n")):
+            result = run_ocr(img)
+        assert result == "Trackliste"
+
+    def test_calls_tesseract_with_correct_args(self, tmp_path: Path) -> None:
+        img = _make_image(tmp_path / "test.jpg")
+        with patch("musiksammlung.ocr.subprocess.run", return_value=_fake_run()) as mock_run:
+            run_ocr(img, languages="deu+eng")
+        args = mock_run.call_args[0][0]
+        assert args[0] == "tesseract"
+        assert str(img) in args
+        assert "deu+eng" in args
+        assert "--psm" in args
+
+    def test_raises_on_nonzero_returncode(self, tmp_path: Path) -> None:
+        img = _make_image(tmp_path / "test.jpg")
+        with patch(
+            "musiksammlung.ocr.subprocess.run",
+            return_value=_fake_run("", returncode=1),
+        ):
+            try:
+                run_ocr(img)
+                assert False, "RuntimeError expected"
+            except RuntimeError as e:
+                assert "Tesseract" in str(e)
+
+    def test_custom_language(self, tmp_path: Path) -> None:
+        img = _make_image(tmp_path / "test.jpg")
+        with patch("musiksammlung.ocr.subprocess.run", return_value=_fake_run()) as mock_run:
+            run_ocr(img, languages="fra")
+        args = mock_run.call_args[0][0]
+        assert "fra" in args
+
+
+# ---------------------------------------------------------------------------
+# _detect_and_fix_rotation
+# ---------------------------------------------------------------------------
+
+
+class TestDetectAndFixRotation:
+    def test_no_rotation_needed(self) -> None:
+        img = Image.new("L", (200, 100))
+        osd_output = "Rotate: 0\nOrientation in degrees: 0\n"
+        with patch("musiksammlung.ocr.subprocess.run", return_value=_fake_run(osd_output)):
+            result = _detect_and_fix_rotation(img)
+        assert result.size == (200, 100)
+
+    def test_rotates_90_degrees(self) -> None:
+        img = Image.new("L", (200, 100))  # breit
+        osd_output = "Rotate: 90\nOrientation in degrees: 90\n"
+        with patch("musiksammlung.ocr.subprocess.run", return_value=_fake_run(osd_output)):
+            result = _detect_and_fix_rotation(img)
+        # 200×100 rotiert um 90° → 100×200
+        assert result.size == (100, 200)
+
+    def test_rotates_180_degrees(self) -> None:
+        img = Image.new("L", (200, 100))
+        osd_output = "Rotate: 180\n"
+        with patch("musiksammlung.ocr.subprocess.run", return_value=_fake_run(osd_output)):
+            result = _detect_and_fix_rotation(img)
+        # 180° Rotation ändert Größe nicht
+        assert result.size == (200, 100)
+
+    def test_fallback_brute_force_when_osd_fails(self) -> None:
+        img = Image.new("L", (200, 100))
+        call_count = [0]
+
+        def side_effect(cmd, **kwargs):
+            call_count[0] += 1
+            if call_count[0] == 1:
+                # Erster Aufruf (OSD) schlägt fehl
+                return _fake_run("", returncode=1)
+            # Weitere Aufrufe (brute-force): 90° liefert die meisten Buchstaben
+            if "--psm" in cmd and "6" in cmd:
+                return _fake_run("Allegro Andante Beethoven" if call_count[0] == 3 else "a")
+            return _fake_run("")
+
+        with patch("musiksammlung.ocr.subprocess.run", side_effect=side_effect):
+            _detect_and_fix_rotation(img)
+        # Brute-force wurde verwendet (mind. 4 Subprocess-Aufrufe)
+        assert call_count[0] >= 2
+
+
+# ---------------------------------------------------------------------------
+# ocr_images
+# ---------------------------------------------------------------------------
+
+
+class TestOcrImages:
+    def test_returns_text_for_single_image(self, tmp_path: Path) -> None:
+        img = _make_image(tmp_path / "img.jpg")
+
+        with (
+            patch("musiksammlung.ocr.preprocess_image", return_value=img),
+            patch("musiksammlung.ocr.run_ocr", return_value="Track 1\nTrack 2"),
+        ):
+            result = ocr_images([img])
+
+        assert result == "Track 1\nTrack 2"
+
+    def test_concatenates_multiple_images(self, tmp_path: Path) -> None:
+        img1 = _make_image(tmp_path / "img1.jpg")
+        img2 = _make_image(tmp_path / "img2.jpg")
+        preprocessed = tmp_path / "pre.png"
+        preprocessed.write_bytes(b"fake")
+
+        with (
+            patch("musiksammlung.ocr.preprocess_image", return_value=preprocessed),
+            patch("musiksammlung.ocr.run_ocr", side_effect=["Text A", "Text B"]),
+        ):
+            result = ocr_images([img1, img2])
+
+        assert result == "Text A\n\nText B"
+
+    def test_skips_empty_ocr_result(self, tmp_path: Path) -> None:
+        img = _make_image(tmp_path / "img.jpg")
+        preprocessed = tmp_path / "pre.png"
+        preprocessed.write_bytes(b"fake")
+
+        with (
+            patch("musiksammlung.ocr.preprocess_image", return_value=preprocessed),
+            patch("musiksammlung.ocr.run_ocr", return_value=""),
+        ):
+            result = ocr_images([img])
+
+        assert result == ""
+
+    def test_cleans_up_temp_file(self, tmp_path: Path) -> None:
+        img = _make_image(tmp_path / "img.jpg")
+        preprocessed = tmp_path / "pre.png"
+        preprocessed.write_bytes(b"fake")
+
+        with (
+            patch("musiksammlung.ocr.preprocess_image", return_value=preprocessed),
+            patch("musiksammlung.ocr.run_ocr", return_value="text"),
+        ):
+            ocr_images([img])
+
+        # Temporäre Datei wurde gelöscht
+        assert not preprocessed.exists()
+
+    def test_cleans_up_even_on_error(self, tmp_path: Path) -> None:
+        img = _make_image(tmp_path / "img.jpg")
+        preprocessed = tmp_path / "pre.png"
+        preprocessed.write_bytes(b"fake")
+
+        err = RuntimeError("Tesseract fehlgeschlagen")
+        with (
+            patch("musiksammlung.ocr.preprocess_image", return_value=preprocessed),
+            patch("musiksammlung.ocr.run_ocr", side_effect=err),
+        ):
+            try:
+                ocr_images([img])
+            except RuntimeError:
+                pass
+
+        assert not preprocessed.exists()