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// Copyright 2009 The Go 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 ring
import (
"fmt"
"testing"
)
// For debugging - keep around.
func dump(r *Ring) {
if r == nil {
fmt.Println("empty")
return
}
i, n := 0, r.Len()
for p := r; i < n; p = p.next {
fmt.Printf("%4d: %p = {<- %p | %p ->}\n", i, p, p.prev, p.next)
i++
}
fmt.Println()
}
func verify(t *testing.T, r *Ring, N int, sum int) {
// Len
n := r.Len()
if n != N {
t.Errorf("r.Len() == %d; expected %d", n, N)
}
// iteration
n = 0
s := 0
for p := range r.Iter() {
n++
if p != nil {
s += p.(int)
}
}
if n != N {
t.Errorf("number of forward iterations == %d; expected %d", n, N)
}
if sum >= 0 && s != sum {
t.Errorf("forward ring sum = %d; expected %d", s, sum)
}
if r == nil {
return
}
// connections
if r.next != nil {
var p *Ring // previous element
for q := r; p == nil || q != r; q = q.next {
if p != nil && p != q.prev {
t.Errorf("prev = %p, expected q.prev = %p\n", p, q.prev)
}
p = q
}
if p != r.prev {
t.Errorf("prev = %p, expected r.prev = %p\n", p, r.prev)
}
}
// Next, Prev
if r.Next() != r.next {
t.Errorf("r.Next() != r.next")
}
if r.Prev() != r.prev {
t.Errorf("r.Prev() != r.prev")
}
// Move
if r.Move(0) != r {
t.Errorf("r.Move(0) != r")
}
if r.Move(N) != r {
t.Errorf("r.Move(%d) != r", N)
}
if r.Move(-N) != r {
t.Errorf("r.Move(%d) != r", -N)
}
for i := 0; i < 10; i++ {
ni := N + i
mi := ni % N
if r.Move(ni) != r.Move(mi) {
t.Errorf("r.Move(%d) != r.Move(%d)", ni, mi)
}
if r.Move(-ni) != r.Move(-mi) {
t.Errorf("r.Move(%d) != r.Move(%d)", -ni, -mi)
}
}
}
func TestCornerCases(t *testing.T) {
var (
r0 *Ring
r1 Ring
)
// Basics
verify(t, r0, 0, 0)
verify(t, &r1, 1, 0)
// Insert
r1.Link(r0)
verify(t, r0, 0, 0)
verify(t, &r1, 1, 0)
// Insert
r1.Link(r0)
verify(t, r0, 0, 0)
verify(t, &r1, 1, 0)
// Unlink
r1.Unlink(0)
verify(t, &r1, 1, 0)
}
func makeN(n int) *Ring {
r := New(n)
for i := 1; i <= n; i++ {
r.Value = i
r = r.Next()
}
return r
}
func sum(r *Ring) int {
s := 0
for p := range r.Iter() {
s += p.(int)
}
return s
}
func sumN(n int) int { return (n*n + n) / 2 }
func TestNew(t *testing.T) {
for i := 0; i < 10; i++ {
r := New(i)
verify(t, r, i, -1)
}
for i := 0; i < 10; i++ {
r := makeN(i)
verify(t, r, i, sumN(i))
}
}
func TestLink1(t *testing.T) {
r1a := makeN(1)
var r1b Ring
r2a := r1a.Link(&r1b)
verify(t, r2a, 2, 1)
if r2a != r1a {
t.Errorf("a) 2-element link failed")
}
r2b := r2a.Link(r2a.Next())
verify(t, r2b, 2, 1)
if r2b != r2a.Next() {
t.Errorf("b) 2-element link failed")
}
r1c := r2b.Link(r2b)
verify(t, r1c, 1, 1)
verify(t, r2b, 1, 0)
}
func TestLink2(t *testing.T) {
var r0 *Ring
r1a := &Ring{Value: 42}
r1b := &Ring{Value: 77}
r10 := makeN(10)
r1a.Link(r0)
verify(t, r1a, 1, 42)
r1a.Link(r1b)
verify(t, r1a, 2, 42+77)
r10.Link(r0)
verify(t, r10, 10, sumN(10))
r10.Link(r1a)
verify(t, r10, 12, sumN(10)+42+77)
}
func TestLink3(t *testing.T) {
var r Ring
n := 1
for i := 1; i < 100; i++ {
n += i
verify(t, r.Link(New(i)), n, -1)
}
}
func TestUnlink(t *testing.T) {
r10 := makeN(10)
s10 := r10.Move(6)
sum10 := sumN(10)
verify(t, r10, 10, sum10)
verify(t, s10, 10, sum10)
r0 := r10.Unlink(0)
verify(t, r0, 0, 0)
r1 := r10.Unlink(1)
verify(t, r1, 1, 2)
verify(t, r10, 9, sum10-2)
r9 := r10.Unlink(9)
verify(t, r9, 9, sum10-2)
verify(t, r10, 9, sum10-2)
}
func TestLinkUnlink(t *testing.T) {
for i := 1; i < 4; i++ {
ri := New(i)
for j := 0; j < i; j++ {
rj := ri.Unlink(j)
verify(t, rj, j, -1)
verify(t, ri, i-j, -1)
ri.Link(rj)
verify(t, ri, i, -1)
}
}
}
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