From 4e8e6cd66154fd385fead535c54cedf45ebdcc36 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Wed, 21 Sep 2016 11:33:47 -0700
Subject: [PATCH] dag: add EdgesFrom, EdgesTo, needs tests

---
 dag/graph.go                            | 26 +++++++++++++++++++++++++
 terraform/transform_destroy_cbd.go      |  3 ++-
 terraform/transform_destroy_cbd_test.go |  5 ++++-
 3 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/dag/graph.go b/dag/graph.go
index 012118057..75bc5dbe5 100644
--- a/dag/graph.go
+++ b/dag/graph.go
@@ -48,6 +48,32 @@ func (g *Graph) Edges() []Edge {
 	return result
 }
 
+// EdgesFrom returns the list of edges from the given source.
+func (g *Graph) EdgesFrom(v Vertex) []Edge {
+	var result []Edge
+	from := hashcode(v)
+	for _, e := range g.Edges() {
+		if hashcode(e.Source()) == from {
+			result = append(result, e)
+		}
+	}
+
+	return result
+}
+
+// EdgesTo returns the list of edges to the given target.
+func (g *Graph) EdgesTo(v Vertex) []Edge {
+	var result []Edge
+	search := hashcode(v)
+	for _, e := range g.Edges() {
+		if hashcode(e.Target()) == search {
+			result = append(result, e)
+		}
+	}
+
+	return result
+}
+
 // HasVertex checks if the given Vertex is present in the graph.
 func (g *Graph) HasVertex(v Vertex) bool {
 	return g.vertices.Include(v)
diff --git a/terraform/transform_destroy_cbd.go b/terraform/transform_destroy_cbd.go
index b398920bc..d2abb7dc8 100644
--- a/terraform/transform_destroy_cbd.go
+++ b/terraform/transform_destroy_cbd.go
@@ -50,7 +50,8 @@ func (t *CBDEdgeTransformer) Transform(g *Graph) error {
 		}
 
 		// Find the destroy edge. There should only be one.
-		for _, e := range g.DownEdges(v).List() {
+		for _, e := range g.EdgesTo(v) {
+			log.Printf("WHAT: %#v", e)
 			// Not a destroy edge, ignore it
 			de, ok := e.(*DestroyEdge)
 			if !ok {
diff --git a/terraform/transform_destroy_cbd_test.go b/terraform/transform_destroy_cbd_test.go
index 7df75dc3d..73314b60b 100644
--- a/terraform/transform_destroy_cbd_test.go
+++ b/terraform/transform_destroy_cbd_test.go
@@ -7,7 +7,8 @@ import (
 
 func TestCBDEdgeTransformer(t *testing.T) {
 	g := Graph{Path: RootModulePath}
-	g.Add(&graphNodeDestroyerTest{AddrString: "test.A"})
+	g.Add(&graphNodeCreatorTest{AddrString: "test.A"})
+	g.Add(&graphNodeDestroyerTest{AddrString: "test.A", CBD: true})
 	g.Add(&graphNodeDestroyerTest{AddrString: "test.B"})
 
 	{
@@ -34,7 +35,9 @@ func TestCBDEdgeTransformer(t *testing.T) {
 }
 
 const testTransformCBDEdgeBasicStr = `
+test.A
 test.A (destroy)
+  test.A
   test.B (destroy)
 test.B (destroy)
 `