Small fixes

finder/test_postcode_cache.py

@@ -0,0 +1,58 @@
+"""Tests for the persistent detail-fetch cache (postcode_cache.py)."""
+
+from postcode_cache import load_cache, save_cache
+
+
+def test_save_then_load_round_trips_str_and_none_values(tmp_path):
+    path = tmp_path / "rightmove.json"
+    data = {"123": "SW9 0HD", "456": None, "789": "E20 1FH"}
+    save_cache(path, data)
+    assert load_cache(path) == data
+
+
+def test_save_then_load_round_trips_nested_dicts(tmp_path):
+    # Zoopla caches a flat dict of primitives (or None) per listing id.
+    path = tmp_path / "zoopla.json"
+    data = {
+        "59888978": {
+            "lat": 51.4,
+            "lng": -0.11,
+            "postcode": "BR1 2AB",
+            "uprn": "100023",
+            "number_or_name": "12",
+            "full_address": "12 High St",
+        },
+        "broken": None,
+    }
+    save_cache(path, data)
+    assert load_cache(path) == data
+
+
+def test_load_missing_file_returns_empty(tmp_path):
+    assert load_cache(tmp_path / "does-not-exist.json") == {}
+
+
+def test_load_corrupt_file_returns_empty(tmp_path):
+    path = tmp_path / "corrupt.json"
+    path.write_text("{not valid json", encoding="utf-8")
+    assert load_cache(path) == {}
+
+
+def test_load_non_object_file_returns_empty(tmp_path):
+    path = tmp_path / "list.json"
+    path.write_text("[1, 2, 3]", encoding="utf-8")
+    assert load_cache(path) == {}
+
+
+def test_save_creates_parent_directory(tmp_path):
+    path = tmp_path / "nested" / "dir" / "cache.json"
+    save_cache(path, {"a": "B1 1AA"})
+    assert path.exists()
+    assert load_cache(path) == {"a": "B1 1AA"}
+
+
+def test_save_overwrites_existing(tmp_path):
+    path = tmp_path / "c.json"
+    save_cache(path, {"a": "X1 1AA"})
+    save_cache(path, {"b": "Y2 2BB"})
+    assert load_cache(path) == {"b": "Y2 2BB"}