self = 
project_id = 'precise-truck-742'
def test_one_row_one_column(self, project_id):
    df = gbq.read_gbq(
        "SELECT 3 as v",
        project_id=project_id,
        credentials=self.credentials,
        dialect="standard",
    )
    expected_result = DataFrame(dict(v=[3]))


  tm.assert_frame_equal(df, expected_result)


E       AssertionError: Attributes of DataFrame.iloc[:, 0] (column name="v") are different

E

E       Attribute "dtype" are different

E       [left]:  Int64

E       [right]: int64
tests/system/test_gbq.py:633: AssertionError