Add full coverage of utility functions (#15995)

The datetime conversion tests just test that we can round-trip correctly for now.

Authors:
  - Lawrence Mitchell (https://github.com/wence-)

Approvers:
  - Thomas Li (https://github.com/lithomas1)
  - Kyle Edwards (https://github.com/KyleFromNVIDIA)

URL: #15995

python/cudf_polars/cudf_polars/utils/dtypes.py

@@ -70,7 +70,7 @@ def from_polars(dtype: pl.DataType) -> plc.DataType:
             return plc.DataType(plc.TypeId.TIMESTAMP_MICROSECONDS)
         elif dtype.time_unit == "ns":
             return plc.DataType(plc.TypeId.TIMESTAMP_NANOSECONDS)
-        assert dtype.time_unit is not None
+        assert dtype.time_unit is not None  # pragma: no cover
         assert_never(dtype.time_unit)
     elif isinstance(dtype, pl.Duration):
         if dtype.time_unit == "ms":
@@ -79,7 +79,7 @@ def from_polars(dtype: pl.DataType) -> plc.DataType:
             return plc.DataType(plc.TypeId.DURATION_MICROSECONDS)
         elif dtype.time_unit == "ns":
             return plc.DataType(plc.TypeId.DURATION_NANOSECONDS)
-        assert dtype.time_unit is not None
+        assert dtype.time_unit is not None  # pragma: no cover
         assert_never(dtype.time_unit)
     elif isinstance(dtype, pl.String):
         return plc.DataType(plc.TypeId.STRING)

python/cudf_polars/cudf_polars/utils/sorting.py

@@ -43,8 +43,8 @@ def sort_order(
         for d in descending
     ]
     null_precedence = []
-    # TODO: use strict=True when we drop py39
-    assert len(descending) == len(nulls_last)
+    if len(descending) != len(nulls_last) or len(descending) != num_keys:
+        raise ValueError("Mismatching length of arguments in sort_order")
     for asc, null_last in zip(column_order, nulls_last):
         if (asc == plc.types.Order.ASCENDING) ^ (not null_last):
             null_precedence.append(plc.types.NullOrder.AFTER)

python/cudf_polars/pyproject.toml

@@ -52,6 +52,13 @@ version = {file = "cudf_polars/VERSION"}
 [tool.pytest.ini_options]
 xfail_strict = true
 
+[tool.coverage.report]
+exclude_also = [
+  "if TYPE_CHECKING:",
+  "class .*\\bProtocol\\):",
+  "assert_never\\("
+]
+
 [tool.ruff]
 line-length = 88
 indent-width = 4

python/cudf_polars/tests/expressions/test_datetime_basic.py

@@ -0,0 +1,34 @@
+# SPDX-FileCopyrightText: Copyright (c) 2024 NVIDIA CORPORATION & AFFILIATES.
+# SPDX-License-Identifier: Apache-2.0
+from __future__ import annotations
+
+import pytest
+
+import polars as pl
+
+from cudf_polars.testing.asserts import assert_gpu_result_equal
+
+
+@pytest.mark.parametrize(
+    "dtype",
+    [
+        pl.Date(),
+        pl.Datetime("ms"),
+        pl.Datetime("us"),
+        pl.Datetime("ns"),
+        pl.Duration("ms"),
+        pl.Duration("us"),
+        pl.Duration("ns"),
+    ],
+    ids=repr,
+)
+def test_datetime_dataframe_scan(dtype):
+    ldf = pl.DataFrame(
+        {
+            "a": pl.Series([1, 2, 3, 4, 5, 6, 7], dtype=dtype),
+            "b": pl.Series([3, 4, 5, 6, 7, 8, 9], dtype=pl.UInt16),
+        }
+    ).lazy()
+
+    query = ldf.select(pl.col("b"), pl.col("a"))
+    assert_gpu_result_equal(query)

python/cudf_polars/tests/utils/test_dtypes.py

@@ -0,0 +1,31 @@
+# SPDX-FileCopyrightText: Copyright (c) 2024 NVIDIA CORPORATION & AFFILIATES.
+# SPDX-License-Identifier: Apache-2.0
+
+from __future__ import annotations
+
+import pytest
+
+import polars as pl
+
+from cudf_polars.utils.dtypes import from_polars
+
+
+@pytest.mark.parametrize(
+    "pltype",
+    [
+        pl.Time(),
+        pl.Struct({"a": pl.Int8, "b": pl.Float32}),
+        pl.Datetime("ms", time_zone="US/Pacific"),
+        pl.Array(pl.Int8, 2),
+        pl.Binary(),
+        pl.Categorical(),
+        pl.Enum(["a", "b"]),
+        pl.Field("a", pl.Int8),
+        pl.Object(),
+        pl.Unknown(),
+    ],
+    ids=repr,
+)
+def test_unhandled_dtype_conversion_raises(pltype):
+    with pytest.raises(NotImplementedError):
+        _ = from_polars(pltype)

python/cudf_polars/tests/utils/test_sorting.py

@@ -0,0 +1,21 @@
+# SPDX-FileCopyrightText: Copyright (c) 2024 NVIDIA CORPORATION & AFFILIATES.
+# SPDX-License-Identifier: Apache-2.0
+
+from __future__ import annotations
+
+import pytest
+
+from cudf_polars.utils.sorting import sort_order
+
+
+@pytest.mark.parametrize(
+    "descending,nulls_last,num_keys",
+    [
+        ([True], [False, True], 3),
+        ([True, True], [False, True, False], 3),
+        ([False, True], [True], 3),
+    ],
+)
+def test_sort_order_raises_mismatch(descending, nulls_last, num_keys):
+    with pytest.raises(ValueError):
+        _ = sort_order(descending, nulls_last=nulls_last, num_keys=num_keys)