text: import pytest
  
  from needlestack.apis import data_sources_pb2
  from needlestack.data_sources import DataSource
  
  
  def test_no_datasource(tmpdir):
      proto = data_sources_pb2.DataSource()
      with pytest.raises(ValueError) as excinfo:
          DataSource.from_proto(proto)
          assert "No valid data source found" in str(excinfo.value)
  