auth/internal/testdata/clientcreds_installed.json

{
    "installed": {
        "client_id": "222-installed.apps.googleusercontent.com",
        "client_secret": "shhhh",
        "auth_uri": "https://accounts.google.com/o/oauth2/auth",
        "token_uri": "https://accounts.google.com/o/oauth2/token",
        "redirect_uris": [
            "https://www.example.com/oauth2callback"
        ]
    }
}