Test case for aws_instances data source

main.tf

provider "aws" {
    region = "us-east-1"
}

data "aws_instances" "boxes" {
  instance_ids = ["i-########", "i-########"]
}

data "template_file" "boxes" {
    template = "$${instance_subnet}"

    vars {
        instance_subnet = "${data.aws_instances.boxes.instances.0.subnet_id}"
    }
}

resource "null_resource" "boxes" {
  triggers {
    template = "${data.template_file.boxes.rendered}"
  }

  provisioner "local-exec" {
    command = "echo \"${data.template_file.boxes.rendered}\" > instances.txt"
  }
}