self = 
project_id = 'precise-truck-742'
def test_should_properly_handle_nullable_booleans(self, project_id):
    query = """SELECT * FROM
                (SELECT BOOLEAN(TRUE) AS nullable_boolean),
                (SELECT NULL AS nullable_boolean)"""
    df = gbq.read_gbq(
        query,
        project_id=project_id,
        credentials=self.credentials,
        dialect="legacy",
    )


  tm.assert_frame_equal(


        df, DataFrame({"nullable_boolean": [True, None]}).astype(object)
    )

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

E

E       Attribute "dtype" are different

E       [left]:  boolean

E       [right]: object
tests/system/test_gbq.py:448: AssertionError