Test fixup

pandas/tests/groupby/test_apply.py

@@ -871,14 +871,20 @@ def test_apply_multi_level_name(category):
     b = [1, 2] * 5
     if category:
         b = pd.Categorical(b, categories=[1, 2, 3])
-        expected_index = pd.CategoricalIndex([1, 2], categories=[1, 2, 3], name="B")
+        expected_index = pd.CategoricalIndex([1, 2, 3], categories=[1, 2, 3], name="B")
+        # GH#40669 - summing an empty frame gives float dtype
+        expected_values = [20.0, 25.0, 0.0]
     else:
         expected_index = Index([1, 2], name="B")
+        expected_values = [20, 25]
+    expected = DataFrame(
+        {"C": expected_values, "D": expected_values}, index=expected_index
+    )
+
     df = DataFrame(
         {"A": np.arange(10), "B": b, "C": list(range(10)), "D": list(range(10))}
     ).set_index(["A", "B"])
     result = df.groupby("B").apply(lambda x: x.sum())
-    expected = DataFrame({"C": [20, 25], "D": [20, 25]}, index=expected_index)
     tm.assert_frame_equal(result, expected)
     assert df.index.names == ["A", "B"]