Add unit test for client
Add unit test for client

digiexchris/cloudsql-proxy,GoogleCloudPlatform/cloud-sql-proxy,digiexchris/cloudsql-proxy,ankushagarwal/cloudsql-proxy,GoogleCloudPlatform/cloud-sql-proxy,ankushagarwal/cloudsql-proxy,pdecat/cloudsql-proxy,pdecat/cloudsql-proxy