unit tests require google application credentials #430
Description
The tests in tests/unit/test_select and test__struct require application credentials to run. Without credentials, running the suite results in errors like:
raise exceptions.DefaultCredentialsError(_HELP_MESSAGE)
google.auth.exceptions.DefaultCredentialsError: Could not automatically determine credentials. Please set GOOGLE_APPLICATION_CREDENTIALS or explicitly create credentials and re-run the application. For more information, please see [https://cloud.google.com/docs/authenticati\](https://cloud.google.com/docs/authenticati%5C)
on/getting-started
The credential requirement prevents them from being pure unit tests and running in any environment.