From 2db33926ac39dafd95f2c62825e74514541caeb8 Mon Sep 17 00:00:00 2001
From: Dan Kortschak <dan@kortschak.io>
Date: Sun, 7 Jun 2020 08:03:22 +0930
Subject: [PATCH] graph/iterator: extend iteration tests and fix counting error

---
 graph/iterator/nodes.go      | 5 +----
 graph/iterator/nodes_test.go | 6 ++++++
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/graph/iterator/nodes.go b/graph/iterator/nodes.go
index beec898f..a8ae68d0 100644
--- a/graph/iterator/nodes.go
+++ b/graph/iterator/nodes.go
@@ -24,10 +24,7 @@ func (n *OrderedNodes) Len() int {
 	if n.idx >= len(n.nodes) {
 		return 0
 	}
-	if n.idx <= 0 {
-		return len(n.nodes)
-	}
-	return len(n.nodes[n.idx:])
+	return len(n.nodes[n.idx+1:])
 }
 
 // Next returns whether the next call of Node will return a valid node.
diff --git a/graph/iterator/nodes_test.go b/graph/iterator/nodes_test.go
index 89e4f317..864acdbe 100644
--- a/graph/iterator/nodes_test.go
+++ b/graph/iterator/nodes_test.go
@@ -34,6 +34,9 @@ func TestOrderedNodesIterate(t *testing.T) {
 			var got []graph.Node
 			for it.Next() {
 				got = append(got, it.Node())
+				if len(got)+it.Len() != len(test.nodes) {
+					t.Errorf("unexpected iterator length during iteration for round %d: got:%d want:%d", i, it.Len(), len(test.nodes)-len(got))
+				}
 			}
 			want := test.nodes
 			if !reflect.DeepEqual(got, want) {
@@ -91,6 +94,9 @@ func TestImplicitNodesIterate(t *testing.T) {
 			var got []graph.Node
 			for it.Next() {
 				got = append(got, it.Node())
+				if len(got)+it.Len() != test.end-test.beg {
+					t.Errorf("unexpected iterator length during iteration for round %d: got:%d want:%d", i, it.Len(), (test.end-test.beg)-len(got))
+				}
 			}
 			if !reflect.DeepEqual(got, test.want) {
 				t.Errorf("unexpected iterator output for round %d: got:%#v want:%#v", i, got, test.want)