async def test_no_credentials_in_manager_or_cache(
      self, manager, mock_tool_context
  ):
    """Test OAuth flow when no credentials exist in manager or cache.

    This tests the scenario where both the manager and cache are empty,
    requiring a new OAuth flow to be initiated.
    """
    # Manager starts with no credentials
    manager.credentials_config.credentials = None
    # Cache is also empty (state dict doesn't contain the key)

    result = await manager.get_valid_credentials(mock_tool_context)

    # Should trigger OAuth flow and return None (flow in progress)
    assert result is None
    mock_tool_context.request_credential.assert_called_once()
Test OAuth flow when no credentials exist in manager or cache.

    This tests the scenario where both the manager and cache are empty,
    requiring a new OAuth flow to be initiated.
    
tests/unittests/tools/bigquery/test_bigquery_credentials_manager.py