.

finder/test_transform.py

@@ -1,4 +1,5 @@
 from transform import (
+    build_listing_url,
     build_register_address,
     clean_listing_address,
     extract_full_postcode,
@@ -173,3 +174,33 @@ def test_rightmove_transform_without_detail_keeps_coordinate_logic() -> None:
     assert result is not None
     assert result["Postcode"] == "SW9 7AA"
     assert result["Postcode source"] == "coordinates"
+
+
+def test_build_listing_url_stamps_channel_from_new_build_flag() -> None:
+    # Resale gets RES_BUY; new builds get RES_NEW.
+    assert build_listing_url("/properties/200", False) == (
+        "https://www.rightmove.co.uk/properties/200#/?channel=RES_BUY"
+    )
+    assert build_listing_url("/properties/200", True) == (
+        "https://www.rightmove.co.uk/properties/200#/?channel=RES_NEW"
+    )
+    # An existing channel/fragment on the source URL is stripped and re-stamped.
+    assert build_listing_url("/properties/200#/?channel=RES_BUY", True) == (
+        "https://www.rightmove.co.uk/properties/200#/?channel=RES_NEW"
+    )
+    # Missing URL stays empty.
+    assert build_listing_url("", True) == ""
+
+
+def test_rightmove_transform_tags_new_builds_res_new() -> None:
+    # The Rightmove search response marks new-build developments with
+    # development=True; transform_property must stamp the listing URL RES_NEW.
+    new_build = {**_rightmove_prop(), "development": True}
+    result = transform_property(new_build, "SW9", StubPostcodeIndex("SW9 7AA"))
+    assert result is not None
+    assert result["Listing URL"].endswith("#/?channel=RES_NEW")
+
+    # Ordinary resale (development absent/false) stays RES_BUY.
+    resale = transform_property(_rightmove_prop(), "SW9", StubPostcodeIndex("SW9 7AA"))
+    assert resale is not None
+    assert resale["Listing URL"].endswith("#/?channel=RES_BUY")