fake_oauthclient.py

import httplib2
from googleapiclient.http import HttpMock


class OAuth2Credentials:

    def set_store(self, store):
        pass

    @classmethod
    def from_json(cls, data):
        return cls()

    def authorize(self, http):
        return httplib2.Http(disable_ssl_certificate_validation=True)

run.py

from googleapiclient import discovery
from oauth2client.file import Storage
store = Storage('testcreds.json')
creds = store.get()
# Now we can use WireMock to stub responses to Google API
mocked_dfa = discovery.build('dfareporting', 'v2.5', credentials=creds, cache_discovery=False)
response = mocked_dfa.reports().list(profileId=123456).execute()

testcreds.json

{
    "_module": "fake_oauthclient",
    "_class": "OAuth2Credentials"
}