test: add parameterized tests for rank and window functions with string partitioning

Author: kosiew

python/tests/test_dataframe.py

@@ -855,6 +855,27 @@ def test_window_functions(partitioned_df, name, expr, result):
     assert table.sort_by("a").to_pydict() == expected
 
 
+@pytest.mark.parametrize("partition", ["c", df_col("c")])
+def test_rank_partition_by_accepts_string(partitioned_df, partition):
+    """Passing a string to partition_by should match using col()."""
+    df = partitioned_df.select(
+        f.rank(order_by=column("a"), partition_by=partition).alias("r")
+    )
+    table = pa.Table.from_batches(df.sort(column("a")).collect())
+    assert table.column("r").to_pylist() == [1, 2, 3, 4, 1, 2, 3]
+
+
+@pytest.mark.parametrize("partition", ["c", df_col("c")])
+def test_window_partition_by_accepts_string(partitioned_df, partition):
+    """Window.partition_by accepts string identifiers."""
+    expr = f.first_value(column("a")).over(
+        Window(partition_by=partition, order_by=column("b"))
+    )
+    df = partitioned_df.select(expr.alias("fv"))
+    table = pa.Table.from_batches(df.sort(column("a")).collect())
+    assert table.column("fv").to_pylist() == [1, 1, 1, 1, 5, 5, 5]
+
+
 @pytest.mark.parametrize(
     ("units", "start_bound", "end_bound"),
     [