Here smart-contracts is a symlink to a project:
/dev/docker-eth-dev/dapps/smart-contracts$ truffle test
ERROR: Cannot start service truffle: oci runtime error: container_linux.go:247: starting container process caused "chdir to cwd (\"/var/dapps/smart-contracts\") set in config.json failed: no such file or directory"
But if I copy the full project into dapps/ it runs okay.