permission_check.py

#!/usr/bin/env python3
# -*- coding:utf-8 -*-
from google.cloud import bigquery
from google.oauth2 import service_account

key_path = 'xxxxxxxxxxxxxxxxxxx.json'
credentials = service_account.Credentials.from_service_account_file(
    key_path,
    scopes=[
        'https://www.googleapis.com/auth/bigquery',
        'https://www.googleapis.com/auth/cloud-platform',
        'https://www.googleapis.com/auth/drive.readonly'
    ],
)


query='''
SELECT count(1) as cnt FROM `dataset.external_table_from_google_sheet`
'''

client = bigquery.Client(
    credentials=credentials,
    project=credentials.project_id,
)
query_job = client.query(query)
rows = query_job.result()
for row in rows:
    print(row.cnt)