fix concat test formatting

Author: iamlemec

pandas/tests/reshape/test_concat.py

@@ -1305,11 +1305,14 @@ def test_concat_same_index_names(self, name_in1, name_in2, name_in3, name_out):
         result = pd.concat(frames, axis=1)
 
         exp_ind = pd.Index(["a", "b", "c", "d", "e"], name=name_out)
-        expected = pd.DataFrame({
-            "x": [0, 1, 2, np.nan, np.nan],
-            "y": [np.nan, 0, 1, 2, np.nan],
-            "z": [np.nan, np.nan, 0, 1, 2],
-        }, index=exp_ind)
+        expected = pd.DataFrame(
+            {
+                "x": [0, 1, 2, np.nan, np.nan],
+                "y": [np.nan, 0, 1, 2, np.nan],
+                "z": [np.nan, np.nan, 0, 1, 2],
+            },
+            index=exp_ind,
+        )
 
         tm.assert_frame_equal(result, expected)