Add batch photo processing with mode-specific LLM sessions and metadata writes

test/test_processing.py

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+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+import pytest
+from PIL import Image
+
+from photools3.models import (
+    LlmResponseCaption,
+    LlmResponseCaptionsAndKeywords,
+    LlmResponseKeywords,
+)
+from photools3.processing import (
+    ProcessingMode,
+    _create_session,
+    process_batch,
+    process_photo,
+)
+
+
+@pytest.fixture
+def image_path(tmp_path):
+    path = tmp_path / "photo.png"
+    Image.new("RGB", (20, 20)).save(path)
+    return path
+
+
+@pytest.mark.parametrize(
+    ("mode", "response", "expected_metadata"),
+    [
+        (
+            ProcessingMode.KEYWORDS,
+            LlmResponseKeywords(tags=["architektur"]),
+            {"caption": None, "keywords": ["architektur"]},
+        ),
+        (
+            ProcessingMode.CAPTIONS,
+            LlmResponseCaption(caption="Ein Haus"),
+            {"caption": "Ein Haus", "keywords": None},
+        ),
+        (
+            ProcessingMode.BOTH,
+            LlmResponseCaptionsAndKeywords(caption="Ein Haus", tags=["architektur"]),
+            {"caption": "Ein Haus", "keywords": ["architektur"]},
+        ),
+    ],
+)
+def test_process_photo_writes_only_requested_metadata(
+    image_path, mode, response, expected_metadata
+):
+    session = MagicMock()
+    session.call.return_value = response
+
+    with (
+        patch("photools3.processing._create_session", return_value=session),
+        patch("photools3.processing.MetadataWriter") as writer_class,
+    ):
+        result = process_photo(image_path, mode)
+
+    assert result == response
+    session.call.assert_called_once()
+    session.close.assert_called_once()
+    writer_class.assert_called_once_with(image_path)
+    writer_class.return_value.write.assert_called_once_with(**expected_metadata)
+
+
+def test_process_photo_does_not_close_a_caller_owned_session(image_path):
+    session = MagicMock()
+    session.call.return_value = LlmResponseCaption(caption="Ein Haus")
+
+    with patch("photools3.processing.MetadataWriter"):
+        process_photo(image_path, ProcessingMode.CAPTIONS, session=session)
+
+    session.close.assert_not_called()
+
+
+@pytest.mark.parametrize(
+    ("mode", "constructor"),
+    [
+        (ProcessingMode.KEYWORDS, "LlmSessionKeywords"),
+        (ProcessingMode.CAPTIONS, "LlmSessionCaption"),
+        (ProcessingMode.BOTH, "LlmSessionCaptionsAndKeywords"),
+    ],
+)
+def test_create_session_selects_mode_specific_response_model(mode, constructor):
+    with patch(f"photools3.processing.{constructor}") as session_class:
+        assert _create_session(mode) is session_class.return_value
+
+    session_class.assert_called_once_with()
+
+
+def test_process_batch_is_sequential_reuses_session_and_continues_after_error():
+    active_photos = 0
+    max_active_photos = 0
+
+    class TrackingPhoto:
+        def __init__(self, path):
+            self.path = path
+
+        def __enter__(self):
+            nonlocal active_photos, max_active_photos
+            active_photos += 1
+            max_active_photos = max(max_active_photos, active_photos)
+            return self
+
+        def __exit__(self, exc_type, exc_value, traceback):
+            nonlocal active_photos
+            active_photos -= 1
+
+    session = MagicMock()
+    response = LlmResponseCaptionsAndKeywords(caption="Ein Haus", tags=["architektur"])
+    session.call.side_effect = [response, RuntimeError("temporary error"), response]
+    paths = [Path("one.jpg"), Path("two.jpg"), Path("three.jpg")]
+
+    with (
+        patch("photools3.processing._create_session", return_value=session),
+        patch("photools3.processing.Photo", TrackingPhoto),
+        patch("photools3.processing.MetadataWriter") as writer_class,
+    ):
+        outcomes = process_batch(paths, ProcessingMode.BOTH)
+
+    assert [outcome.succeeded for outcome in outcomes] == [True, False, True]
+    assert [outcome.path for outcome in outcomes] == paths
+    assert outcomes[1].error == "RuntimeError: temporary error"
+    assert max_active_photos == 1
+    assert active_photos == 0
+    assert session.call.call_count == 3
+    assert all(len(call.args[0]) == 1 for call in session.call.call_args_list)
+    assert writer_class.return_value.write.call_count == 2
+    session.close.assert_called_once()