#### Environment details **N/A** - latest #### Steps to reproduce this is the only usage: https://github.com/googleapis/python-spanner/blob/131246cc127003e9bb9c7d46d7c2a1a198f48696/google/cloud/spanner_v1/testing/interceptors.py#L16 it should be an optional dependency and not in `install_requires`: https://github.com/googleapis/python-spanner/blob/131246cc127003e9bb9c7d46d7c2a1a198f48696/setup.py#L46 perhaps an `extras_require` named `testing` ? #### Code example N/A #### Stack trace N/A