rackspace adopt stack op and unit test
diff --git a/rackspace/orchestration/v1/stacks/delegate.go b/rackspace/orchestration/v1/stacks/delegate.go
index e9d74db..5fa8c90 100644
--- a/rackspace/orchestration/v1/stacks/delegate.go
+++ b/rackspace/orchestration/v1/stacks/delegate.go
@@ -10,3 +10,9 @@
 func Create(c *gophercloud.ServiceClient, opts os.CreateOptsBuilder) os.CreateResult {
 	return os.Create(c, opts)
 }
+
+// Adopt accepts an os.AdoptOpts struct and creates a new stack from existing stack
+// resources using the values provided.
+func Adopt(c *gophercloud.ServiceClient, opts os.AdoptOptsBuilder) os.AdoptResult {
+	return os.Adopt(c, opts)
+}