From c8df3e59956969014af6c8e20822ef38d82294dc Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Sun, 8 Jan 2017 11:59:18 -0800
Subject: [PATCH] dag: string DotOpts through to vertex

Fixes #11052

It appears that historically nodes did not expect DotOpts to ever be
nil. To avoid nil panics in general I'm in agreement with this behavior
so this modifies dag to always pass in a non-nil DotOpts. Tests
included.
---
 dag/dot.go      |  6 +++---
 dag/dot_test.go | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 3 deletions(-)
 create mode 100644 dag/dot_test.go

diff --git a/dag/dot.go b/dag/dot.go
index 2deb7ccd3..7e6d2af3b 100644
--- a/dag/dot.go
+++ b/dag/dot.go
@@ -79,7 +79,7 @@ func (g *marshalGraph) Dot(opts *DotOpts) []byte {
 	return w.Bytes()
 }
 
-func (v *marshalVertex) dot(g *marshalGraph) []byte {
+func (v *marshalVertex) dot(g *marshalGraph, opts *DotOpts) []byte {
 	var buf bytes.Buffer
 	graphName := g.Name
 	if graphName == "" {
@@ -89,7 +89,7 @@ func (v *marshalVertex) dot(g *marshalGraph) []byte {
 	name := v.Name
 	attrs := v.Attrs
 	if v.graphNodeDotter != nil {
-		node := v.graphNodeDotter.DotNode(name, nil)
+		node := v.graphNodeDotter.DotNode(name, opts)
 		if node == nil {
 			return []byte{}
 		}
@@ -171,7 +171,7 @@ func (g *marshalGraph) writeBody(opts *DotOpts, w *indentWriter) {
 			continue
 		}
 
-		w.Write(v.dot(g))
+		w.Write(v.dot(g, opts))
 	}
 
 	var dotEdges []string
diff --git a/dag/dot_test.go b/dag/dot_test.go
new file mode 100644
index 000000000..1c28ae68a
--- /dev/null
+++ b/dag/dot_test.go
@@ -0,0 +1,39 @@
+package dag
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestGraphDot_opts(t *testing.T) {
+	var v testDotVertex
+	var g Graph
+	g.Add(&v)
+
+	opts := &DotOpts{MaxDepth: 42}
+	actual := g.Dot(opts)
+	if len(actual) == 0 {
+		t.Fatal("should not be empty")
+	}
+
+	if !v.DotNodeCalled {
+		t.Fatal("should call DotNode")
+	}
+	if !reflect.DeepEqual(v.DotNodeOpts, opts) {
+		t.Fatalf("bad; %#v", v.DotNodeOpts)
+	}
+}
+
+type testDotVertex struct {
+	DotNodeCalled bool
+	DotNodeTitle  string
+	DotNodeOpts   *DotOpts
+	DotNodeReturn *DotNode
+}
+
+func (v *testDotVertex) DotNode(title string, opts *DotOpts) *DotNode {
+	v.DotNodeCalled = true
+	v.DotNodeTitle = title
+	v.DotNodeOpts = opts
+	return v.DotNodeReturn
+}