Add a random string to ad directory so tests can be run in parallel (G…

…oogleCloudPlatform#3802)

* Add a random string to ad directory so tests can be run in parallel

* Add import

third_party/terraform/tests/resource_active_directory_domain_update_test.go

@@ -1,6 +1,7 @@
 package google
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/hashicorp/terraform-plugin-sdk/helper/resource"
@@ -9,8 +10,9 @@ import (
 func TestAccActiveDirectoryDomain_update(t *testing.T) {
 	t.Parallel()
 
+	domain := fmt.Sprintf("mydomain%s.org1.com", randString(t, 5))
 	context := map[string]interface{}{
-		"domain":        "mydomain.org1.com",
+		"domain":        domain,
 		"resource_name": "ad-domain",
 	}