From 8e4bd669e8ab238781fddbd3994314f8a6c62688 Mon Sep 17 00:00:00 2001
From: James Bardin <j.bardin@gmail.com>
Date: Wed, 10 Jun 2020 23:01:00 -0400
Subject: [PATCH] test Set.Copy, Graph.UpEdges, Graph.DownEdges

---
 dag/graph_test.go | 36 ++++++++++++++++++++++++++++++++++++
 dag/set_test.go   | 20 ++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/dag/graph_test.go b/dag/graph_test.go
index 2979744316..76c47641da 100644
--- a/dag/graph_test.go
+++ b/dag/graph_test.go
@@ -170,6 +170,42 @@ func TestGraphEdgesTo(t *testing.T) {
 	}
 }
 
+func TestGraphUpdownEdges(t *testing.T) {
+	// Verify that we can't inadvertently modify the internal graph sets
+	var g Graph
+	g.Add(1)
+	g.Add(2)
+	g.Add(3)
+	g.Connect(BasicEdge(1, 2))
+	g.Connect(BasicEdge(2, 3))
+
+	up := g.UpEdges(2)
+	if up.Len() != 1 || !up.Include(1) {
+		t.Fatalf("expected only an up edge of '1', got %#v", up)
+	}
+	// modify the up set
+	up.Add(9)
+
+	orig := g.UpEdges(2)
+	diff := up.Difference(orig)
+	if diff.Len() != 1 || !diff.Include(9) {
+		t.Fatalf("expected a diff of only '9', got %#v", diff)
+	}
+
+	down := g.DownEdges(2)
+	if down.Len() != 1 || !down.Include(3) {
+		t.Fatalf("expected only a down edge of '3', got %#v", down)
+	}
+	// modify the down set
+	down.Add(8)
+
+	orig = g.DownEdges(2)
+	diff = down.Difference(orig)
+	if diff.Len() != 1 || !diff.Include(8) {
+		t.Fatalf("expected a diff of only '8', got %#v", diff)
+	}
+}
+
 type hashVertex struct {
 	code interface{}
 }
diff --git a/dag/set_test.go b/dag/set_test.go
index 63b72e3239..36bd6a65b8 100644
--- a/dag/set_test.go
+++ b/dag/set_test.go
@@ -99,3 +99,23 @@ func TestSetFilter(t *testing.T) {
 		})
 	}
 }
+
+func TestSetCopy(t *testing.T) {
+	a := make(Set)
+	a.Add(1)
+	a.Add(2)
+
+	b := a.Copy()
+	b.Add(3)
+
+	diff := b.Difference(a)
+
+	if diff.Len() != 1 {
+		t.Fatalf("expected single diff value, got %#v", diff)
+	}
+
+	if !diff.Include(3) {
+		t.Fatalf("diff does not contain 3, got %#v", diff)
+	}
+
+}