use DataFrame instead of pd.DataFrame for test

Author: ntachukwu

pandas/tests/groupby/test_apply.py

@@ -1334,8 +1334,10 @@ def test_result_name_when_one_group(name):
 
 
 def test_empty_df():
- empty_df = pd.DataFrame({"a": [], "b": []})
+ empty_df = DataFrame({"a": [], "b": []})
+
+ # Both operations should return an empty series instead of IndexError for apply UDF
  result = empty_df.groupby("a").b.apply(lambda x: x.values[-1])
- expected = empty_df.groupby("a").b.take([0])
+ expected = empty_df.groupby("a").b.agg("sum")
 
  tm.assert_series_equal(result, expected)