fix error in test code

sklearn/datasets/tests/test_base.py

@@ -171,7 +171,7 @@ def test_load_diabetes():
     res = load_diabetes()
     assert_equal(res.data.shape, (442, 10))
     assert_true(res.target.size, 442)
-    assert_equal(res.feature_names.size, 10)
+    assert_equal(len(res.feature_names), 10)
 
     # test return_X_y option
     X_y_tuple = load_diabetes(return_X_y=True)