test(#134): wahlprogramm_fetch Coverage 42.8% → 54.4%

8 zusaetzliche Tests:
- TestLockFileRobustness: kaputtes JSON, fehlende Datei, _save_lock-Roundtrip
- TestLoadLinks: missing yaml + empty yaml (gestubbed)
- TestGetMissingProgrammes: leere/gefuellte Eintraege, Bundesland-Filter

yaml ist im Unit-Setup gestubbed; Tests patchen _load_links direkt
statt echte YAML-Parsing zu erzwingen — die echte Datei-Validierung
gehoert in die integration-Suite gegen die produktive links.yaml.

tests/test_wahlprogramm_fetch.py

@@ -300,6 +300,88 @@ class TestShaLock:
         assert lock["spd-mv.pdf"] == _sha(content)
 
 
+# ---------------------------------------------------------------------------
+# Test 5: Lock-File und YAML-Robustheit (#134 Coverage-Backfill)
+# ---------------------------------------------------------------------------
+
+class TestLockFileRobustness:
+    def test_corrupt_lock_file_returns_empty_dict(self, tmp_path):
+        """Kaputtes JSON darf den Caller nicht crashen — leeren Lock liefern."""
+        from app.wahlprogramm_fetch import _load_lock
+        bad = tmp_path / "broken-lock.json"
+        bad.write_text("{ this is not json ;)")
+        with patch("app.wahlprogramm_fetch._LOCK_FILE", bad):
+            result = _load_lock()
+        assert result == {}
+
+    def test_missing_lock_file_returns_empty_dict(self, tmp_path):
+        from app.wahlprogramm_fetch import _load_lock
+        missing = tmp_path / "no-such-file.json"
+        with patch("app.wahlprogramm_fetch._LOCK_FILE", missing):
+            assert _load_lock() == {}
+
+    def test_save_lock_writes_valid_json(self, tmp_path):
+        from app.wahlprogramm_fetch import _save_lock
+        target = tmp_path / "lock.json"
+        with patch("app.wahlprogramm_fetch._LOCK_FILE", target):
+            _save_lock({"x.pdf": "abc123", "y.pdf": "def456"})
+        import json
+        loaded = json.loads(target.read_text())
+        assert loaded == {"x.pdf": "abc123", "y.pdf": "def456"}
+
+
+class TestLoadLinks:
+    def test_missing_yaml_returns_empty(self, tmp_path):
+        from app.wahlprogramm_fetch import _load_links
+        with patch("app.wahlprogramm_fetch._LINKS_FILE", tmp_path / "missing.yaml"):
+            assert _load_links() == {}
+
+    def test_empty_yaml_returns_empty(self, tmp_path):
+        from app.wahlprogramm_fetch import _load_links
+        target = tmp_path / "empty.yaml"
+        target.write_text("")
+        with patch("app.wahlprogramm_fetch._LINKS_FILE", target):
+            assert _load_links() == {}
+
+    # Hinweis: yaml ist im Unit-Setup gestubbed (siehe Top-of-File), deshalb
+    # testen wir _load_links nur mit existing-vs-missing-File. Die echte
+    # YAML-Parsing-Logik wird in der integration-Suite gegen die echte
+    # links.yaml validiert.
+
+
+class TestGetMissingProgrammes:
+    """Tests fuer get_missing_programmes — listet BL/Partei-Kombinationen mit
+    Kandidaten-URL aber fehlender lokaler Datei. yaml ist gestubbed; Tests
+    patchen daher _load_links direkt."""
+
+    def test_no_yaml_returns_empty(self):
+        from app.wahlprogramm_fetch import get_missing_programmes
+        with patch("app.wahlprogramm_fetch._load_links", return_value={}):
+            assert get_missing_programmes() == []
+
+    def test_lists_entries_when_file_missing(self, tmp_path):
+        """Eintrag in YAML, registriertes WAHLPROGRAMME-File fehlt → listed."""
+        from app.wahlprogramm_fetch import get_missing_programmes
+        fake_links = {"BX": {"XYZ": [{"url": "https://example.com/x.pdf"}]}}
+        with patch("app.wahlprogramm_fetch._load_links", return_value=fake_links):
+            with patch("app.wahlprogramm_fetch._REFERENZEN_DIR", tmp_path / "ref"):
+                missing = get_missing_programmes()
+        codes = [m["bl"] for m in missing]
+        assert "BX" in codes
+
+    def test_bundesland_filter(self, tmp_path):
+        from app.wahlprogramm_fetch import get_missing_programmes
+        fake_links = {
+            "BX": {"XYZ": [{"url": "https://example.com/x.pdf"}]},
+            "BY": {"ABC": [{"url": "https://example.com/y.pdf"}]},
+        }
+        with patch("app.wahlprogramm_fetch._load_links", return_value=fake_links):
+            with patch("app.wahlprogramm_fetch._REFERENZEN_DIR", tmp_path / "ref"):
+                missing = get_missing_programmes(bundesland="BX")
+        codes = {m["bl"] for m in missing}
+        assert codes == {"BX"}
+
+
 # ---------------------------------------------------------------------------
 # Test 4: og_card — cache_key Determinismus und Cache-Miss/Hit
 # ---------------------------------------------------------------------------