dnsclient_test.go

     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  	"testing"
     9  )
    10  
    11  func checkDistribution(t *testing.T, data []*SRV, margin float64) {
    12  	sum := 0
    13  	for _, srv := range data {
    14  		sum += int(srv.Weight)
    15  	}
    16  
    17  	results := make(map[string]int)
    18  
    19  	count := 10000
    20  	for j := 0; j < count; j++ {
    21  		d := make([]*SRV, len(data))
    22  		copy(d, data)
    23  		byPriorityWeight(d).shuffleByWeight()
    24  		key := d[0].Target
    25  		results[key] = results[key] + 1
    26  	}
    27  
    28  	actual := results[data[0].Target]
    29  	expected := float64(count) * float64(data[0].Weight) / float64(sum)
    30  	diff := float64(actual) - expected
    31  	t.Logf("actual: %v diff: %v e: %v m: %v", actual, diff, expected, margin)
    32  	if diff < 0 {
    33  		diff = -diff
    34  	}
    35  	if diff > (expected * margin) {
    36  		t.Errorf("missed target weight: expected %v, %v", expected, actual)
    37  	}
    38  }
    39  
    40  func testUniformity(t *testing.T, size int, margin float64) {
    41  	data := make([]*SRV, size)
    42  	for i := 0; i < size; i++ {
    43  		data[i] = &SRV{Target: string('a' + rune(i)), Weight: 1}
    44  	}
    45  	checkDistribution(t, data, margin)
    46  }
    47  
    48  func TestDNSSRVUniformity(t *testing.T) {
    49  	testUniformity(t, 2, 0.05)
    50  	testUniformity(t, 3, 0.10)
    51  	testUniformity(t, 10, 0.20)
    52  	testWeighting(t, 0.05)
    53  }
    54  
    55  func testWeighting(t *testing.T, margin float64) {
    56  	data := []*SRV{
    57  		{Target: "a", Weight: 60},
    58  		{Target: "b", Weight: 30},
    59  		{Target: "c", Weight: 10},
    60  	}
    61  	checkDistribution(t, data, margin)
    62  }
    63  
    64  func TestWeighting(t *testing.T) {
    65  	testWeighting(t, 0.05)
    66  }
    67
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