test(module): fix test module invocation

main.tftest.hcl

@@ -5,11 +5,10 @@ provider "aws" {
 
 run "main" {
   assert {
-    condition     = output.arn != null
+    condition     = module.main.arn != null
     error_message = "invalid IAM role ARN"
   }
+  module {
+    source = "./test"
   }
-
-variables {
-  name = "tftest-role"
 }