Fix: call heapify on delete

src/calendar_queue/calendar_queue.py

@@ -8,6 +8,7 @@
 from asyncio import Queue, QueueFull, TimerHandle
 from heapq import heappop as heap_pop
 from heapq import heappush as heap_push
+from heapq import heapify
 import math
 import sys
 from time import time
@@ -237,6 +238,10 @@ def delete_items(
             if selector(item):
                 del_items.append(self._queue.pop(q_len - 1 - i))
 
+        # Restore heap invariant after arbitrary deletions.
+        if del_items:
+            heapify(self._queue)
+
         self._update_timer()
 
         return del_items

tests/test_calendar_queue.py

@@ -111,6 +111,41 @@ async def test_delete_items():
     assert cq.qsize() == 5
 
 
+@pytest.mark.asyncio
+async def test_delete_restores_heap_property():
+    """Ensure deleting arbitrary items restores the heap property so
+    subsequent pops return items in increasing timestamp order.
+    """
+
+    cq = CalendarQueue()
+
+    base_ts = time()
+
+    items = [
+        (base_ts + 10, "a"),
+        (base_ts + 20, "b"),
+        (base_ts + 30, "c"),
+        (base_ts + 40, "d"),
+    ]
+
+    for item in items:
+        cq.put_nowait(item)
+
+    # remove the middle element
+    deleted = cq.delete_items(lambda x: x[1] == "b")
+
+    assert len(deleted) == 1 and deleted[0] == (base_ts + 20, "b")
+
+    popped = []
+    while cq.qsize() > 0:
+        popped.append(cq.get_nowait())
+
+    assert [p[1] for p in popped] == ["a", "c", "d"]
+    assert popped[0][0] == pytest.approx(base_ts + 10, abs=ABS_TOLERANCE)
+    assert popped[1][0] == pytest.approx(base_ts + 30, abs=ABS_TOLERANCE)
+    assert popped[2][0] == pytest.approx(base_ts + 40, abs=ABS_TOLERANCE)
+
+
 @pytest.mark.asyncio
 async def test_far_schedule():
     """Test putting an event scheduled far in time.