From 6d8dd5f29ef03eaf7427e44362644e8746357e3f Mon Sep 17 00:00:00 2001
From: MarcoGorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Fri, 8 Sep 2023 14:05:28 +0200
Subject: [PATCH 1/2] fix(python, rust): enforce sortedness of by argument in
 rolling_* functions

---
 crates/polars-plan/src/dsl/mod.rs              |  3 +++
 .../unit/operations/rolling/test_rolling.py    | 18 ++++++++++++++++--
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/crates/polars-plan/src/dsl/mod.rs b/crates/polars-plan/src/dsl/mod.rs
index 6267a8e42354..fca087abf8b1 100644
--- a/crates/polars-plan/src/dsl/mod.rs
+++ b/crates/polars-plan/src/dsl/mod.rs
@@ -1,5 +1,7 @@
 #![allow(ambiguous_glob_reexports)]
 //! Domain specific language for the Lazy API.
+#[cfg(feature = "rolling_window")]
+use polars_core::utils::ensure_sorted_arg;
 #[cfg(feature = "dtype-categorical")]
 pub mod cat;
 #[cfg(feature = "dtype-categorical")]
@@ -1240,6 +1242,7 @@ impl Expr {
                         ),
                         _ => (by.clone(), &None),
                     };
+                    ensure_sorted_arg(&by, expr_name)?;
                     let by = by.datetime().unwrap();
                     let by_values = by.cont_slice().map_err(|_| {
                         polars_err!(
diff --git a/py-polars/tests/unit/operations/rolling/test_rolling.py b/py-polars/tests/unit/operations/rolling/test_rolling.py
index e9b6e616f5ca..17d8bfd0f783 100644
--- a/py-polars/tests/unit/operations/rolling/test_rolling.py
+++ b/py-polars/tests/unit/operations/rolling/test_rolling.py
@@ -48,7 +48,7 @@ def example_df() -> pl.DataFrame:
 def test_rolling_kernels_and_group_by_rolling(
     example_df: pl.DataFrame, period: str | timedelta, closed: ClosedInterval
 ) -> None:
-    out1 = example_df.select(
+    out1 = example_df.set_sorted("dt").select(
         [
             pl.col("dt"),
             # this differs from group_by aggregation because the empty window is
@@ -789,7 +789,7 @@ def test_rolling_empty_window_9406() -> None:
         "d",
         [datetime(2019, 1, x) for x in [16, 17, 18, 22, 23]],
         dtype=pl.Datetime(time_unit="us", time_zone=None),
-    )
+    ).set_sorted()
     rawdata = pl.Series("x", [1.1, 1.2, 1.3, 1.15, 1.25], dtype=pl.Float64)
     rmin = pl.Series("x", [None, 1.1, 1.1, None, 1.15], dtype=pl.Float64)
     rmax = pl.Series("x", [None, 1.1, 1.2, None, 1.15], dtype=pl.Float64)
@@ -834,6 +834,20 @@ def test_rolling_weighted_quantile_10031() -> None:
     )
 
 
+def test_rolling_aggregations_unsorted_raise_10991() -> None:
+    df = pl.DataFrame(
+        {
+            "dt": [datetime(2020, 1, 3), datetime(2020, 1, 1), datetime(2020, 1, 2)],
+            "val": [1, 2, 3],
+        }
+    )
+    with pytest.raises(
+        pl.InvalidOperationError,
+        match="argument in operation 'rolling_sum' is not explicitly sorted",
+    ):
+        df.with_columns(roll=pl.col("val").rolling_sum("2d", by="dt", closed="right"))
+
+
 def test_rolling() -> None:
     a = pl.Series("a", [1, 2, 3, 2, 1])
     assert_series_equal(a.rolling_min(2), pl.Series("a", [None, 1, 2, 2, 1]))

From 306418b5488ad256f6c8c86d135cbab588dda0b0 Mon Sep 17 00:00:00 2001
From: MarcoGorelli <33491632+MarcoGorelli@users.noreply.github.com>
Date: Tue, 12 Sep 2023 20:40:45 +0200
Subject: [PATCH 2/2] post-merge fixup

---
 py-polars/tests/unit/operations/rolling/test_rolling.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/py-polars/tests/unit/operations/rolling/test_rolling.py b/py-polars/tests/unit/operations/rolling/test_rolling.py
index 37a61493c6b0..27f57e660a7c 100644
--- a/py-polars/tests/unit/operations/rolling/test_rolling.py
+++ b/py-polars/tests/unit/operations/rolling/test_rolling.py
@@ -928,7 +928,7 @@ def test_rolling_nanoseconds_11003() -> None:
             "val": [1, 2, 3],
         }
     )
-    df = df.with_columns(pl.col("dt").str.to_datetime(time_unit="ns"))
+    df = df.with_columns(pl.col("dt").str.to_datetime(time_unit="ns")).set_sorted("dt")
     result = df.with_columns(
         pl.col("val").rolling_sum("500ns", by="dt", closed="right")
     )