parameterize test_window_functions

`first_value` and `last_value` are currently failing and marked as xfail.

Author: Michael-J-Ward

python/datafusion/tests/test_dataframe.py

@@ -278,63 +278,50 @@ def test_distinct():
     assert df_a.collect() == df_b.collect()
 
 
-def test_window_functions(df):
+data_test_window_functions = [
+ ("row", f.window("row_number", [], order_by=[f.order_by(column("c"))]), [2, 1, 3]),
+ ("rank", f.window("rank", [], order_by=[f.order_by(column("c"))]), [2, 1, 2]),
+ ("dense_rank", f.window("dense_rank", [], order_by=[f.order_by(column("c"))]),  [2, 1, 2] ),
+ ("percent_rank", f.window("percent_rank", [], order_by=[f.order_by(column("c"))]), [0.5, 0, 0.5]),
+ ("cume_dist", f.window("cume_dist", [], order_by=[f.order_by(column("b"))]), [0.3333333333333333, 0.6666666666666666, 1.0]),
+ ("ntile", f.window("ntile", [literal(2)], order_by=[f.order_by(column("c"))]), [1, 1, 2]),
+ ("next", f.window("lead", [column("b")], order_by=[f.order_by(column("b"))]), [5, 6, None]),
+ ("previous", f.window("lag", [column("b")], order_by=[f.order_by(column("b"))]), [None, 4, 5]),
+ pytest.param(
+    "first_value",
+    f.window(
+        "first_value",
+        [column("a")],
+        order_by=[f.order_by(column("b"))]
+    ),
+    [1, 1, 1],
+    marks=pytest.mark.xfail,
+ ),
+ pytest.param(
+    "last_value",
+    f.window("last_value", [column("b")], order_by=[f.order_by(column("b"))]),
+    [4, 5, 6],
+    marks=pytest.mark.xfail,
+ ),
+ pytest.param(
+    "2nd_value",
+    f.window(
+        "nth_value",
+        [column("b"), literal(2)],
+        order_by=[f.order_by(column("b"))],
+    ),
+    [None, 5, 5],
+ ),
+]
+
+
+@pytest.mark.parametrize("name,expr,result", data_test_window_functions)
+def test_window_functions(df, name, expr, result):
     df = df.select(
         column("a"),
         column("b"),
         column("c"),
-        f.alias(
-            f.window("row_number", [], order_by=[f.order_by(column("c"))]),
-            "row",
-        ),
-        f.alias(
-            f.window("rank", [], order_by=[f.order_by(column("c"))]),
-            "rank",
-        ),
-        f.alias(
-            f.window("dense_rank", [], order_by=[f.order_by(column("c"))]),
-            "dense_rank",
-        ),
-        f.alias(
-            f.window("percent_rank", [], order_by=[f.order_by(column("c"))]),
-            "percent_rank",
-        ),
-        f.alias(
-            f.window("cume_dist", [], order_by=[f.order_by(column("b"))]),
-            "cume_dist",
-        ),
-        f.alias(
-            f.window("ntile", [literal(2)], order_by=[f.order_by(column("c"))]),
-            "ntile",
-        ),
-        f.alias(
-            f.window("lag", [column("b")], order_by=[f.order_by(column("b"))]),
-            "previous",
-        ),
-        f.alias(
-            f.window("lead", [column("b")], order_by=[f.order_by(column("b"))]),
-            "next",
-        ),
-        f.alias(
-            f.window(
-                "first_value",
-                [column("a")],
-                order_by=[f.order_by(column("b"))],
-            ),
-            "first_value",
-        ),
-        f.alias(
-            f.window("last_value", [column("b")], order_by=[f.order_by(column("b"))]),
-            "last_value",
-        ),
-        f.alias(
-            f.window(
-                "nth_value",
-                [column("b"), literal(2)],
-                order_by=[f.order_by(column("b"))],
-            ),
-            "2nd_value",
-        ),
+        f.alias(expr, name)
     )
 
     table = pa.Table.from_batches(df.collect())
@@ -343,18 +330,9 @@ def test_window_functions(df):
         "a": [1, 2, 3],
         "b": [4, 5, 6],
         "c": [8, 5, 8],
-        "row": [2, 1, 3],
-        "rank": [2, 1, 2],
-        "dense_rank": [2, 1, 2],
-        "percent_rank": [0.5, 0, 0.5],
-        "cume_dist": [0.3333333333333333, 0.6666666666666666, 1.0],
-        "ntile": [1, 1, 2],
-        "next": [5, 6, None],
-        "previous": [None, 4, 5],
-        "first_value": [1, 1, 1],
-        "last_value": [4, 5, 6],
-        "2nd_value": [None, 5, 5],
+        name: result
     }
+
     assert table.sort_by("a").to_pydict() == expected