Adding more tests and delete fn
diff --git a/openstack/db/v1/instances/results.go b/openstack/db/v1/instances/results.go
index 562f752..d2ea794 100644
--- a/openstack/db/v1/instances/results.go
+++ b/openstack/db/v1/instances/results.go
@@ -40,6 +40,10 @@
 	commonResult
 }
 
+type DeleteResult struct {
+	gophercloud.ErrResult
+}
+
 func (r commonResult) Extract() (*Instance, error) {
 	if r.Err != nil {
 		return nil, r.Err