add tests for piping fmt
add tests for piping fmt

rnaveiras/packer,rnaveiras/packer,mitchellh/packer,pecigonzalo/packer,hashicorp/packer,rnaveiras/packer,pecigonzalo/packer,mitchellh/packer,mitchellh/packer,hashicorp/packer,mitchellh/packer,hashicorp/packer,mitchellh/packer,rnaveiras/packer,rnaveiras/packer,rnaveiras/packer,pecigonzalo/packer,pecigonzalo/packer,hashicorp/packer