test(tradein): assert config kwarg on cian price-history fetch_detail call (#2306)

code-reviewer flagged that neither the new parity test nor
test_backfill_wave2.py's 3 cian_price_history tests would catch a
regression if config=RealScraperConfig() were accidentally dropped from
the fetch_detail call in cian_price_history.py (the proxy-footgun fix
from the #2306 migration) — mock_fetch.assert_called_once() doesn't
check kwargs.

Strengthens all 3 tests (saves_changes / skips_no_changes /
handles_fetch_none) to assert isinstance(call_kwargs["config"],
RealScraperConfig). Manually verified the guard actually catches the
regression: temporarily removed config= from cian_price_history.py:110,
confirmed all 3 tests fail, restored the fix, confirmed they pass again.

tradein-mvp/backend/tests/test_backfill_wave2.py

@@ -235,6 +235,7 @@ async def test_backfill_yandex_addresses_error_on_non_200():
 async def test_cian_price_history_saves_changes():
     """Happy path: fetch returns DetailEnrichment with price_changes → saved."""
     from app.services.cian_price_history import backfill_cian_price_history
+    from app.services.scraper_adapters import RealScraperConfig
     from app.services.scrapers.cian_detail import DetailEnrichment
 
     enrichment = DetailEnrichment(
@@ -277,6 +278,12 @@ async def test_cian_price_history_saves_changes():
     assert result.saved == 2  # 2 price_changes
     assert result.errors == 0
     mock_fetch.assert_called_once()
+    # #2306 regression guard: kit fetch_detail silently drops the Cian proxy
+    # (direct connection, #806 ban risk) unless config=RealScraperConfig() is
+    # passed at the call site — assert_called_once() alone wouldn't catch someone
+    # dropping that kwarg later.
+    _, call_kwargs = mock_fetch.call_args
+    assert isinstance(call_kwargs.get("config"), RealScraperConfig)
     mock_save.assert_called_once()
 
 
@@ -284,6 +291,7 @@ async def test_cian_price_history_saves_changes():
 async def test_cian_price_history_skips_no_changes():
     """Fetch succeeds but no price_changes → skipped (not error)."""
     from app.services.cian_price_history import backfill_cian_price_history
+    from app.services.scraper_adapters import RealScraperConfig
     from app.services.scrapers.cian_detail import DetailEnrichment
 
     enrichment = DetailEnrichment(cian_id=111, price_changes=[])
@@ -296,7 +304,7 @@ async def test_cian_price_history_skips_no_changes():
             "app.services.cian_price_history.fetch_detail",
             new_callable=AsyncMock,
             return_value=enrichment,
-        ),
+        ) as mock_fetch,
         patch("app.services.cian_price_history.save_detail_enrichment") as mock_save,
         patch("app.services.cian_price_history.get_scraper_delay", return_value=0.0),
     ):
@@ -309,12 +317,16 @@ async def test_cian_price_history_skips_no_changes():
     assert result.skipped == 1
     assert result.saved == 0
     mock_save.assert_not_called()
+    # #2306 regression guard — see test_cian_price_history_saves_changes.
+    _, call_kwargs = mock_fetch.call_args
+    assert isinstance(call_kwargs.get("config"), RealScraperConfig)
 
 
 @pytest.mark.asyncio
 async def test_cian_price_history_handles_fetch_none():
     """fetch_detail returns None → errors+1, no crash."""
     from app.services.cian_price_history import backfill_cian_price_history
+    from app.services.scraper_adapters import RealScraperConfig
 
     mock_db = MagicMock()
     rows = [{"id": 30, "source_url": "https://ekb.cian.ru/sale/flat/999/"}]
@@ -324,7 +336,7 @@ async def test_cian_price_history_handles_fetch_none():
             "app.services.cian_price_history.fetch_detail",
             new_callable=AsyncMock,
             return_value=None,
-        ),
+        ) as mock_fetch,
         patch("app.services.cian_price_history.get_scraper_delay", return_value=0.0),
     ):
         mock_mappings = MagicMock()
@@ -335,6 +347,9 @@ async def test_cian_price_history_handles_fetch_none():
 
     assert result.errors == 1
     assert result.saved == 0
+    # #2306 regression guard — see test_cian_price_history_saves_changes.
+    _, call_kwargs = mock_fetch.call_args
+    assert isinstance(call_kwargs.get("config"), RealScraperConfig)
 
 
 # ============================================================================