refactor: fix groupby.GroupBy.first doctest for sqlglot

Author: chelsea-lin

bigframes/core/compile/sqlglot/compiler.py

@@ -378,7 +378,7 @@ def compile_window(node: nodes.WindowOpNode, child: ir.SQLGlotIR) -> ir.SQLGlotI
             window_op = sge.Case(ifs=when_expressions, default=window_op)
 
         # TODO: check if we can directly window the expression.
-        result = child.window(
+        result = result.window(
             window_op=window_op,
             output_column_id=cdef.id.sql,
         )

tests/unit/core/compile/sqlglot/snapshots/test_compile_window/test_compile_window_w_groupby_rolling/out.sql

@@ -12,12 +12,32 @@ WITH `bfcte_0` AS (
     `int64_col` AS `bfcol_8`,
     `bool_col` AS `bfcol_9`
   FROM `bfcte_0`
-), `bfcte_3` AS (
+), `bfcte_2` AS (
   SELECT
     *
   FROM `bfcte_1`
   WHERE
     NOT `bfcol_9` IS NULL
+), `bfcte_3` AS (
+  SELECT
+    *,
+    CASE
+      WHEN SUM(CAST(NOT `bfcol_7` IS NULL AS INT64)) OVER (
+        PARTITION BY `bfcol_9`
+        ORDER BY `bfcol_9` ASC NULLS LAST, `rowindex` ASC NULLS LAST
+        ROWS BETWEEN 3 PRECEDING AND CURRENT ROW
+      ) < 3
+      THEN NULL
+      ELSE COALESCE(
+        SUM(CAST(`bfcol_7` AS INT64)) OVER (
+          PARTITION BY `bfcol_9`
+          ORDER BY `bfcol_9` ASC NULLS LAST, `rowindex` ASC NULLS LAST
+          ROWS BETWEEN 3 PRECEDING AND CURRENT ROW
+        ),
+        0
+      )
+    END AS `bfcol_15`
+  FROM `bfcte_2`
 ), `bfcte_4` AS (
   SELECT
     *,