try to reproduce #8730 in tests

hcl2template/testdata/complete/build.pkr.hcl

@@ -8,7 +8,7 @@ build {
     provisioner "shell" {
         name     = "provisioner that does something"
         not_squashed = var.foo
-        string   = "string"
+        string   = "string${var.proxmox_username}"
         int      = "${41 + 1}"
         int64    = "${42 + 1}"
         bool     = "true"

hcl2template/testdata/complete/variables.pkr.hcl

@@ -10,6 +10,10 @@ variable "image_id" {
   default = "image-id-default"
 }
 
+variable "proxmox_username" {
+  type = string
+}
+
 variable "port" {
   type = number
   default = 42

hcl2template/types.packer_config_test.go

@@ -25,6 +25,7 @@ func TestParser_complete(t *testing.T) {
 					"image_id":                &Variable{},
 					"port":                    &Variable{},
 					"availability_zone_names": &Variable{},
+					"proxmox_username":        &Variable{},
 				},
 				LocalVariables: Variables{
 					"feefoo": &Variable{},