Merge pull request 'added price drops to alerts/fixed race condition where late claimed docs got their tags wiped and sent to the api without tags' (#19) from development into main

Reviewed-on: #19

src/monitor_utils/database.py

@@ -282,16 +282,19 @@ def extract_recorded_prices(existing_doc: dict | None) -> set[float]:
 def build_alert(monitor_name: str, document: dict, now: datetime) -> dict:
     """Build an alert referencing a product for consumer delivery.
 
-    The alert carries its own copy of the document's newListing flag: the
+    The alert carries its own copy of the document's newListing flag and
-    product doc is rewritten every cycle, so its flag flips False one cycle
+    priceBeforeDrop: the product doc is rewritten every cycle, so its flag
-    after discovery, while a discovery alert may sit in a backed-up queue
+    flips False one cycle after discovery and its priceBeforeDrop is
-    longer than that. The alert's copy is written once and cannot rot.
+    cleared by the next cycle that sees no drop, while an alert may sit in
+    a backed-up queue longer than that. The alert's copies are written once
+    and cannot rot.
 
     Args:
         monitor_name: Monitor that produced the product, used by the
             consumer to resolve the owning collection and thresholds.
         document: Product document supplying the id, pricing for the
-            priority calculation, and the stamped newListing flag.
+            priority calculation, and the stamped newListing flag and
+            priceBeforeDrop.
         now: Detection timestamp stored as createdAt.
 
     Returns:
@@ -306,6 +309,7 @@ def build_alert(monitor_name: str, document: dict, now: datetime) -> dict:
         "attempts": 0,
         "createdAt": now,
         "newListing": document.get("newListing", False),
+        "priceBeforeDrop": document.get("priceBeforeDrop"),
     }
 
 

tests/test_new_listing_stamp.py

@@ -99,6 +99,32 @@ def test_existing_doc_with_new_price_stamps_false():
     assert alert_doc(collection)["newListing"] is False
 
 
+def test_drop_alert_carries_price_before_drop():
+    """the doc's priceBeforeDrop is cleared by the next no-drop cycle, so the
+    alert keeps its own copy from emit time — a drop claimed late still knows
+    what it dropped from"""
+
+    existing = {"_id": "p1", "currentPrice": 100.0, "pastPrices": []}
+    collection = FakeCollection([existing])
+    run(collection, [_product(current=95.0)])
+
+    assert alert_doc(collection)["priceBeforeDrop"] == 100.0
+
+
+def test_non_drop_alert_carries_none():
+    """a never-seen higher price alerts without a drop; discoveries have no
+    prior price at all"""
+
+    existing = {"_id": "p1", "currentPrice": 100.0, "pastPrices": []}
+    collection = FakeCollection([existing])
+    run(collection, [_product(current=120.0)])
+    assert alert_doc(collection)["priceBeforeDrop"] is None
+
+    discovery = FakeCollection()
+    run(discovery, [_product()])
+    assert alert_doc(discovery)["priceBeforeDrop"] is None
+
+
 def test_existing_doc_with_known_price_emits_no_alert():
     existing = {
         "_id": "p1",
@@ -112,8 +138,9 @@ def test_existing_doc_with_known_price_emits_no_alert():
     assert collection.alerts is None
 
 
-def test_build_alert_defaults_missing_flag_to_false():
+def test_build_alert_defaults_missing_fields():
     """Direct callers passing an unstamped document must not KeyError."""
 
     alert = build_alert("bestbuy", {"_id": "p1"}, NOW)
     assert alert["newListing"] is False
+    assert alert["priceBeforeDrop"] is None