fix: support groupby.iter for cudf (#1265)

Author: MarcoGorelli

narwhals/_pandas_like/group_by.py

@@ -103,15 +103,16 @@ def _from_native_frame(self, df: PandasLikeDataFrame) -> PandasLikeDataFrame:
 
     def __iter__(self) -> Iterator[tuple[Any, PandasLikeDataFrame]]:
         indices = self._grouped.indices
-        for key in indices:
-            if (
-                self._df._implementation is Implementation.PANDAS
-                and self._df._backend_version < (2, 2)
-            ):  # pragma: no cover
-                pass
-            else:  # pragma: no cover
+        if (
+            self._df._implementation is Implementation.PANDAS
+            and self._df._backend_version < (2, 2)
+        ) or (self._df._implementation is Implementation.CUDF):  # pragma: no cover
+            for key in indices:
+                yield (key, self._from_native_frame(self._grouped.get_group(key)))
+        else:
+            for key in indices:
                 key = tupleify(key)  # noqa: PLW2901
-            yield (key, self._from_native_frame(self._grouped.get_group(key)))
+                yield (key, self._from_native_frame(self._grouped.get_group(key)))
 
 
 def agg_pandas(  # noqa: PLR0915

tests/group_by_test.py

@@ -74,12 +74,7 @@ def test_invalid_group_by() -> None:
         )
 
 
-def test_group_by_iter(
-    constructor_eager: ConstructorEager, request: pytest.FixtureRequest
-) -> None:
-    if "cudf" in str(constructor_eager):
-        # https://github.com/rapidsai/cudf/issues/17187
-        request.applymarker(pytest.mark.xfail)
+def test_group_by_iter(constructor_eager: ConstructorEager) -> None:
     df = nw.from_native(constructor_eager(data), eager_only=True)
     expected_keys = [(1,), (3,)]
     keys = []