Move tests to pytest-grpc

https://github.com/kataev/pytest-grpc

This will allow invoking servicers directly with pytest --grpc-fake-server for nicer error tracing and speed boost.

[kalvdans]

Thanks! Then I will go on with it and clean it up 😃

[aapeliv]

Just to clarify: when they made that plugin, there was no interceptor support in gRPC. They’ve since added that support, and indeed, it’s easy now to use that to verify a user has a valid bearer token.

The tricky part is in propagating the user_id down to the RPC handlers through the context. That’s the part I didn’t figure out how to do without this custom interceptor code.