1 // Copyright 2014 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package net 6 7 import ( 8 "math/rand" 9 "testing" 10 ) 11 12 func checkDistribution(t *testing.T, data []*SRV, margin float64) { 13 sum := 0 14 for _, srv := range data { 15 sum += int(srv.Weight) 16 } 17 18 results := make(map[string]int) 19 20 count := 1000 21 for j := 0; j < count; j++ { 22 d := make([]*SRV, len(data)) 23 copy(d, data) 24 byPriorityWeight(d).shuffleByWeight() 25 key := d[0].Target 26 results[key] = results[key] + 1 27 } 28 29 actual := results[data[0].Target] 30 expected := float64(count) * float64(data[0].Weight) / float64(sum) 31 diff := float64(actual) - expected 32 t.Logf("actual: %v diff: %v e: %v m: %v", actual, diff, expected, margin) 33 if diff < 0 { 34 diff = -diff 35 } 36 if diff > (expected * margin) { 37 t.Errorf("missed target weight: expected %v, %v", expected, actual) 38 } 39 } 40 41 func testUniformity(t *testing.T, size int, margin float64) { 42 rand.Seed(1) 43 data := make([]*SRV, size) 44 for i := 0; i < size; i++ { 45 data[i] = &SRV{Target: string('a' + i), Weight: 1} 46 } 47 checkDistribution(t, data, margin) 48 } 49 50 func TestDNSSRVUniformity(t *testing.T) { 51 testUniformity(t, 2, 0.05) 52 testUniformity(t, 3, 0.10) 53 testUniformity(t, 10, 0.20) 54 testWeighting(t, 0.05) 55 } 56 57 func testWeighting(t *testing.T, margin float64) { 58 rand.Seed(1) 59 data := []*SRV{ 60 {Target: "a", Weight: 60}, 61 {Target: "b", Weight: 30}, 62 {Target: "c", Weight: 10}, 63 } 64 checkDistribution(t, data, margin) 65 } 66 67 func TestWeighting(t *testing.T) { 68 testWeighting(t, 0.05) 69 } 70
