async () => {
   const oauth2client =
       new googleapis.auth.OAuth2(CLIENT_ID, CLIENT_SECRET, REDIRECT_URI);
   oauth2client.credentials = {refresh_token: 'abc'};
   await assertRejects(
       oauth2client.revokeCredentials(),
       /Error: No access token to revoke./);
   assert.deepStrictEqual(oauth2client.credentials, {});
 });
async function testNoTokens(urlshortener: APIEndpoint, client: OAuth2Client) {
  await assertRejects(
      urlshortener.url.get({shortUrl: '123', auth: client}),
      /No access, refresh token or API key is set./);
}