fix: handle Unicode normalization in save_dict for umlauts (#728) (#729)

tests/unit/test_dicts.py

@@ -0,0 +1,40 @@
+# SPDX-FileCopyrightText: © Sebastian Thomschke and contributors
+# SPDX-License-Identifier: AGPL-3.0-or-later
+# SPDX-ArtifactOfProjectHomePage: https://github.com/Second-Hand-Friends/kleinanzeigen-bot/
+"""Tests for the dicts utility module."""
+import unicodedata
+from pathlib import Path
+
+
+def test_save_dict_normalizes_unicode_paths(tmp_path:Path) -> None:
+    """Test that save_dict normalizes paths to NFC for cross-platform consistency (issue #728).
+
+    Directories are created with NFC normalization (via sanitize_folder_name).
+    This test verifies save_dict's defensive normalization handles edge cases where
+    an NFD path is passed (e.g., "ä" as "a" + combining diacritic vs single character).
+    It should normalize to NFC and use the existing NFC directory.
+    """
+    from kleinanzeigen_bot.utils import dicts  # noqa: PLC0415
+
+    # Create directory with NFC normalization (as sanitize_folder_name does)
+    title_nfc = unicodedata.normalize("NFC", "KitchenAid Zuhälter - nie benutzt")
+    nfc_dir = tmp_path / f"ad_12345_{title_nfc}"
+    nfc_dir.mkdir(parents = True)
+
+    # Call save_dict with NFD path (different normalization)
+    title_nfd = unicodedata.normalize("NFD", title_nfc)
+    assert title_nfc != title_nfd, "NFC and NFD should be different strings"
+
+    nfd_path = tmp_path / f"ad_12345_{title_nfd}" / "ad_12345.yaml"
+    dicts.save_dict(str(nfd_path), {"test": "data", "title": title_nfc})
+
+    # Verify file was saved successfully
+    nfc_files = list(nfc_dir.glob("*.yaml"))
+    assert len(nfc_files) == 1, "Should have exactly one file in NFC directory"
+    assert nfc_files[0].name == "ad_12345.yaml"
+
+    # On macOS/APFS, the filesystem normalizes both NFC and NFD to the same directory
+    # On Linux ext4, NFC normalization in save_dict ensures it uses the existing directory
+    # Either way, we should have exactly one YAML file total (no duplicates)
+    all_yaml_files = list(tmp_path.rglob("*.yaml"))
+    assert len(all_yaml_files) == 1, f"Expected exactly 1 YAML file total, found {len(all_yaml_files)}: {all_yaml_files}"

tests/unit/test_extract.py

@@ -1225,3 +1225,71 @@ class TestAdExtractorDownload:
             assert result_dir.exists()
             assert (result_dir / "existing_image.jpg").exists()  # File should be preserved
             assert ad_cfg.title == "Test Title"
+
+    @pytest.mark.asyncio
+    async def test_download_ad_with_umlauts_in_title(self, extractor:AdExtractor, tmp_path:Path) -> None:
+        """Test cross-platform Unicode handling for ad titles with umlauts (issue #728).
+
+        Verifies that:
+        1. Directories are created with NFC-normalized names (via sanitize_folder_name)
+        2. Files can be saved to those directories (via save_dict's NFC normalization)
+        3. No FileNotFoundError occurs due to NFC/NFD mismatch on Linux/Windows
+        """
+        # Title with German umlauts (ä) - common in real ads
+        title_with_umlauts = "KitchenAid Zuhälter - nie benutzt"
+
+        # Mock the page
+        page_mock = MagicMock()
+        page_mock.url = "https://www.kleinanzeigen.de/s-anzeige/test/12345"
+        extractor.page = page_mock
+
+        base_dir = tmp_path / "downloaded-ads"
+        base_dir.mkdir()
+
+        with patch.object(extractor, "web_text", new_callable = AsyncMock, side_effect = [
+                title_with_umlauts,  # Title extraction
+                title_with_umlauts,  # Second title call for full extraction
+                "Description text",  # Description
+                "03.02.2025"  # Creation date
+            ]), \
+                patch.object(extractor, "web_execute", new_callable = AsyncMock, return_value = {
+                    "universalAnalyticsOpts": {
+                        "dimensions": {
+                            "dimension92": "",
+                            "dimension108": ""
+                        }
+                    }
+                }), \
+                patch.object(extractor, "_extract_category_from_ad_page", new_callable = AsyncMock, return_value = "160"), \
+                patch.object(extractor, "_extract_special_attributes_from_ad_page", new_callable = AsyncMock, return_value = {}), \
+                patch.object(extractor, "_extract_pricing_info_from_ad_page", new_callable = AsyncMock, return_value = (None, "NOT_APPLICABLE")), \
+                patch.object(extractor, "_extract_shipping_info_from_ad_page", new_callable = AsyncMock, return_value = ("NOT_APPLICABLE", None, None)), \
+                patch.object(extractor, "_extract_sell_directly_from_ad_page", new_callable = AsyncMock, return_value = False), \
+                patch.object(extractor, "_download_images_from_ad_page", new_callable = AsyncMock, return_value = []), \
+                patch.object(extractor, "_extract_contact_from_ad_page", new_callable = AsyncMock, return_value = ContactPartial(
+                    name = "Test", zipcode = "12345", location = "Berlin"
+                )):
+
+            ad_cfg, result_dir = await extractor._extract_ad_page_info_with_directory_handling(
+                base_dir, 12345
+            )
+
+            # Verify directory was created with NFC-normalized name
+            assert result_dir.exists()
+            assert ad_cfg.title == title_with_umlauts
+
+            # Test saving YAML file to the Unicode directory path
+            # Before fix: Failed on Linux/Windows due to NFC/NFD mismatch
+            # After fix: Both directory and file use NFC normalization
+            ad_file_path = Path(result_dir) / "ad_12345.yaml"
+
+            from kleinanzeigen_bot.utils import dicts  # noqa: PLC0415
+
+            header_string = "# yaml-language-server: $schema=https://raw.githubusercontent.com/Second-Hand-Friends/kleinanzeigen-bot/refs/heads/main/schemas/ad.schema.json"
+
+            # save_dict normalizes path to NFC, matching the NFC directory name
+            dicts.save_dict(str(ad_file_path), ad_cfg.model_dump(), header = header_string)
+
+            # Verify file was created successfully (no FileNotFoundError)
+            assert ad_file_path.exists()
+            assert ad_file_path.is_file()

tests/unit/test_utils_misc.py

@@ -144,9 +144,9 @@ def test_ensure_non_callable_truthy_and_falsy() -> None:
         # Basic sanitization
         ("My Ad Title!", "My Ad Title!", "Basic sanitization"),
 
-        # Unicode normalization (sanitize-filename changes normalization)
-        ("café", "cafe\u0301", "Unicode normalization"),
-        ("caf\u00e9", "cafe\u0301", "Unicode normalization from escaped"),
+        # Unicode normalization - sanitize-filename converts to NFD, then we normalize to NFC (issue #728)
+        ("café", "café", "Unicode NFC → NFD (by sanitize) → NFC (by normalize)"),
+        ("caf\u00e9", "café", "Unicode NFC (escaped) → NFD → NFC"),
 
         # Edge cases
         ("", "untitled", "Empty string"),