fix: tolerate malformed GraphQL payloads in parsers

py_gasbuddy/parsers.py

@@ -25,19 +25,31 @@ def parse_distance(value: Any) -> float | None:
         return None
 
 
-def build_discount_map(offers: list[dict[str, Any]]) -> dict[str, float]:
+def build_discount_map(offers: list[Any]) -> dict[str, float]:
     """Return fuel product key to total pwgbDiscount mapping across all offers."""
     discount_map: dict[str, float] = {}
     for offer in offers:
-        for disc in offer.get("discounts") or []:
+        if not isinstance(offer, dict):
+            continue
+        discounts = offer.get("discounts")
+        if not isinstance(discounts, list):
+            continue
+        for disc in discounts:
+            if not isinstance(disc, dict):
+                continue
             raw = disc.get("pwgbDiscount")
             if raw is None:
                 continue
             try:
                 amount = float(raw)
             except (ValueError, TypeError):
                 continue
-            for grade in disc.get("grades") or []:
+            grades = disc.get("grades")
+            if not isinstance(grades, list):
+                continue
+            for grade in grades:
+                if not isinstance(grade, str):
+                    continue
                 discount_map[grade] = discount_map.get(grade, 0.0) + amount
     return discount_map
 
@@ -46,8 +58,12 @@ def format_price_node(
     price_node: dict[str, Any], deal_discount: float | None = None
 ) -> PriceNode:
     """Format a single price node."""
-    credit_data = price_node.get("credit") or {}
-    cash_data = price_node.get("cash") or {}
+    credit_data = price_node.get("credit")
+    if not isinstance(credit_data, dict):
+        credit_data = {}
+    cash_data = price_node.get("cash")
+    if not isinstance(cash_data, dict):
+        cash_data = {}
 
     credit_price = credit_data.get("price", 0)
     cash_price = cash_data.get("price", 0)
@@ -67,15 +83,39 @@ def format_price_node(
     )
 
 
+def _stations_block(response: dict[str, Any]) -> dict[str, Any]:
+    """Return the ``stations`` dict from a locationBySearchTerm response.
+
+    Defensive against the GraphQL spec's allowance of partial responses
+    (``data: null``, missing keys, ``stations`` being null or a non-dict).
+    Returns an empty dict when the expected shape isn't present so callers
+    can downgrade to "no results" rather than crash.
+    """
+    data = response.get("data")
+    if not isinstance(data, dict):
+        return {}
+    location = data.get("locationBySearchTerm")
+    if not isinstance(location, dict):
+        return {}
+    stations = location.get("stations")
+    return stations if isinstance(stations, dict) else {}
+
+
 def parse_cursor(response: dict[str, Any]) -> str | None:
     """Extract the next-page cursor from a locationBySearchTerm response."""
-    stations = response["data"]["locationBySearchTerm"]["stations"]
-    return (stations.get("cursor") or {}).get("next")
+    stations = _stations_block(response)
+    cursor = stations.get("cursor")
+    if not isinstance(cursor, dict):
+        return None
+    return cursor.get("next")
 
 
 def parse_location_results(response: dict[str, Any]) -> LocationSearchResult:
     """Parse location search results into a LocationSearchResult."""
-    stations = response["data"]["locationBySearchTerm"]["stations"]
+    stations = _stations_block(response)
+    raw_results = stations.get("results") or []
+    if not isinstance(raw_results, list):
+        raw_results = []
     results = [
         cast(
             StationSummary,
@@ -91,7 +131,8 @@ def parse_location_results(response: dict[str, Any]) -> LocationSearchResult:
                 "price_unit": r.get("priceUnit"),
             },
         )
-        for r in stations["results"]
+        for r in raw_results
+        if isinstance(r, dict) and "id" in r
     ]
     return cast(
         LocationSearchResult,
@@ -102,7 +143,15 @@ def parse_location_results(response: dict[str, Any]) -> LocationSearchResult:
 def parse_results(response: dict[str, Any], limit: int) -> list[StationPrice]:
     """Parse price-service API results into a StationPrice list."""
     result_list: list[StationPrice] = []
-    results = response["data"]["locationBySearchTerm"]["stations"]["results"]
+    raw_results = _stations_block(response).get("results") or []
+    if not isinstance(raw_results, list):
+        raw_results = []
+    required_station_keys = {"id", "priceUnit", "currency", "latitude", "longitude"}
+    results = [
+        r
+        for r in raw_results
+        if isinstance(r, dict) and required_station_keys.issubset(r)
+    ]
 
     for result in results[:limit]:
         raw: dict[str, Any] = {
@@ -128,21 +177,26 @@ def parse_results(response: dict[str, Any], limit: int) -> list[StationPrice]:
             "phone": result.get("phone") or None,
         }
         pay_status_obj = result.get("payStatus")
-        is_pay_available = (pay_status_obj is None) or bool(
-            (pay_status_obj or {}).get("isPayAvailable", False)
+        is_pay_available = (pay_status_obj is None) or (
+            isinstance(pay_status_obj, dict)
+            and bool(pay_status_obj.get("isPayAvailable", False))
         )
         raw["pay_status"] = is_pay_available
-        offers = result.get("offers") or []
+        offers = [o for o in (result.get("offers") or []) if isinstance(o, dict)]
         discount_map = build_discount_map(offers) if is_pay_available else {}
         for price in result.get("prices") or []:
+            if not isinstance(price, dict) or "fuelProduct" not in price:
+                continue
             fuel_key = price["fuelProduct"]
             raw[fuel_key] = format_price_node(price, discount_map.get(fuel_key))
         result_list.append(cast(StationPrice, raw))
     return result_list
 
 
-def parse_ev_stations(stations_data: list[dict[str, Any]]) -> list[EvStation]:
+def parse_ev_stations(stations_data: Any) -> list[EvStation]:
     """Parse raw EV station dicts into EvStation list."""
+    if not isinstance(stations_data, list):
+        return []
     return [
         cast(
             EvStation,
@@ -179,16 +233,30 @@ def parse_ev_stations(stations_data: list[dict[str, Any]]) -> list[EvStation]:
             },
         )
         for s in stations_data
+        if isinstance(s, dict) and "id" in s
     ]
 
 
 def parse_trends(response: dict[str, Any]) -> list[TrendData]:
     """Parse price-service API results into a TrendData list."""
+    data = response.get("data")
+    if not isinstance(data, dict):
+        return []
+    location = data.get("locationBySearchTerm")
+    if not isinstance(location, dict):
+        return []
+    trends = location.get("trends") or []
+    if not isinstance(trends, list):
+        return []
     return [
         TrendData(
             average_price=trend["today"],
             lowest_price=trend["todayLow"],
             area=trend["areaName"],
         )
-        for trend in response["data"]["locationBySearchTerm"]["trends"]
+        for trend in trends
+        if isinstance(trend, dict)
+        and "today" in trend
+        and "todayLow" in trend
+        and "areaName" in trend
     ]

tests/test_init.py

@@ -338,7 +338,10 @@ async def test_retry_logic(mock_aioclient, caplog):
     )
     # Patch asyncio.sleep used by backoff so the test doesn't actually
     # wait through the exponential delay between retries.
-    with caplog.at_level(logging.DEBUG), patch("backoff._async.asyncio.sleep", new=AsyncMock()):
+    with (
+        caplog.at_level(logging.DEBUG),
+        patch("backoff._async.asyncio.sleep", new=AsyncMock()),
+    ):
         with pytest.raises(py_gasbuddy.LibraryError):
             manager = py_gasbuddy.GasBuddy(station_id=205033)
             await manager.price_lookup()
@@ -358,11 +361,14 @@ async def test_retry_succeeds_on_second_attempt(mock_aioclient, caplog):
     mock_aioclient.post(
         TEST_URL,
         status=403,
-        body='<!DOCTYPE html><html><title>Just a moment...</title></html>',
+        body="<!DOCTYPE html><html><title>Just a moment...</title></html>",
     )
     mock_aioclient.post(TEST_URL, status=200, body=load_fixture("station.json"))
 
-    with caplog.at_level(logging.DEBUG), patch("backoff._async.asyncio.sleep", new=AsyncMock()):
+    with (
+        caplog.at_level(logging.DEBUG),
+        patch("backoff._async.asyncio.sleep", new=AsyncMock()),
+    ):
         manager = py_gasbuddy.GasBuddy(station_id=205033)
         data = await manager.price_lookup()