graph/testgraph: add mutation tests

graph/testgraph/testgraph_test.go

@@ -0,0 +1,80 @@
+// Copyright ©2019 The Gonum Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package testgraph
+
+import (
+	"reflect"
+	"testing"
+
+	"gonum.org/v1/gonum/graph"
+	"gonum.org/v1/gonum/graph/simple"
+)
+
+var randomNodesTests = []struct {
+	n    int
+	seed uint64
+	new  func(int64) graph.Node
+	want []graph.Node
+}{
+	{
+		n:    0,
+		want: nil,
+	},
+	{
+		n:    1,
+		seed: 1,
+		new:  newSimpleNode,
+		want: []graph.Node{simple.Node(-106976941678315313)},
+	},
+	{
+		n:    1,
+		seed: 2,
+		new:  newSimpleNode,
+		want: []graph.Node{simple.Node(6816453162648937526)},
+	},
+	{
+		n:    4,
+		seed: 1,
+		new:  newSimpleNode,
+		want: []graph.Node{
+			simple.Node(-106976941678315313),
+			simple.Node(867649948573917593),
+			simple.Node(-4246677790793934368),
+			simple.Node(406519965772129914),
+		},
+	},
+	{
+		n:    4,
+		seed: 2,
+		new:  newSimpleNode,
+		want: []graph.Node{
+			simple.Node(6816453162648937526),
+			simple.Node(-4921844272880608907),
+			simple.Node(159088832891557680),
+			simple.Node(-2611333848016927708),
+		},
+	},
+}
+
+func newSimpleNode(id int64) graph.Node { return simple.Node(id) }
+
+func TestRandomNodesIterate(t *testing.T) {
+	for _, test := range randomNodesTests {
+		for i := 0; i < 2; i++ {
+			it := NewRandomNodes(test.n, test.seed, test.new)
+			if it.Len() != len(test.want) {
+				t.Errorf("unexpected iterator length for round %d: got:%d want:%d", i, it.Len(), len(test.want))
+			}
+			var got []graph.Node
+			for it.Next() {
+				got = append(got, it.Node())
+			}
+			if !reflect.DeepEqual(got, test.want) {
+				t.Errorf("unexpected iterator output for round %d: got:%#v want:%#v", i, got, test.want)
+			}
+			it.Reset()
+		}
+	}
+}