add e2e test for the failed case

Signed-off-by: Richard Chien <stdrc@outlook.com>

e2e_test/udf/bug_fixes/17560_udaf_as_win_func.slt

@@ -17,3 +17,69 @@ select t.value, sum00(weight) OVER (PARTITION BY value) from (values (1, 1), (nu
 ----
 1 1
 3 3
+
+statement ok
+drop aggregate sum00;
+
+# https://github.com/risingwavelabs/risingwave/issues/18436
+
+statement ok
+CREATE TABLE exam_scores (
+  score_id int,
+  exam_id int,
+  student_id int,
+  score real,
+  exam_date timestamp
+);
+
+statement ok
+INSERT INTO exam_scores (score_id, exam_id, student_id, score, exam_date)
+VALUES
+  (1, 101, 1001, 85.5, '2022-01-10'),
+  (2, 101, 1002, 92.0, '2022-01-10'),
+  (3, 101, 1003, 78.5, '2022-01-10'),
+  (4, 102, 1001, 91.2, '2022-02-15'),
+  (5, 102, 1003, 88.9, '2022-02-15');
+
+statement ok
+create aggregate weighted_avg(value float, weight float) returns float language python as $$
+def create_state():
+    return (0, 0)
+def accumulate(state, value, weight):
+    if value is None or weight is None:
+        return state
+    (s, w) = state
+    s += value * weight
+    w += weight
+    return (s, w)
+def retract(state, value, weight):
+    if value is None or weight is None:
+        return state
+    (s, w) = state
+    s -= value * weight
+    w -= weight
+    return (s, w)
+def finish(state):
+    (sum, weight) = state
+    if weight == 0:
+        return None
+    else:
+        return sum / weight
+$$;
+
+query
+SELECT
+    *,
+    weighted_avg(score, 1) OVER (
+        PARTITION BY "student_id"
+        ORDER BY "exam_date"
+        ROWS 2 PRECEDING
+    ) AS "weighted_avg"
+FROM exam_scores
+ORDER BY "student_id", "exam_date";
+----
+1	101	1001	85.5	2022-01-10 00:00:00	85.5
+4	102	1001	91.2	2022-02-15 00:00:00	88.3499984741211
+2	101	1002	92	2022-01-10 00:00:00	92
+3	101	1003	78.5	2022-01-10 00:00:00	78.5
+5	102	1003	88.9	2022-02-15 00:00:00	83.70000076293945