Create helper function in pandas/tests/io/json/test_pandas.py
A lot of the tests in that module repeat the following pattern:

```python
if orient == "records" or orient == "values":
    expected = expected.reset_index(drop=True)
if orient == "values":
    expected.columns = range(len(expected.columns))

assert_frame_equal(result, expected)
```

This is because the `records` and `values` formats intentionally do not completely preserve the axes labels. It would be nice to refactor this into a dedicated helper function (`assert_json_roundtrip_equal`?)