uuid/uuid_test.go at master · as/uuid · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
package uuid

import (
	"math"
	"testing"
	"time"
)

var (
	N = 1024 * 1024
)

func TestV4(t *testing.T) {
	saw := make(map[string]bool)
	t.Log(V4())
	for i := 0; i < N; i++ {
		saw[V4()] = true
	}
	t.Log(V4())
	if len(saw) != N {
		t.Fatalf("have %d distinct, want %d", len(saw), N)
	}
}

func TestValid(t *testing.T) {
	for i, s := range []string{
		"00000000-0000-0000-0000-000000000000",
		"bb1c05dd-c584-7b82-32e9-94d689898560",
		"BB1C05DD-C584-7B82-32E9-94D689898560",
		"BB1C05DD-CCCC-CCCC-CCCC-DDDDEEEEFFFF",
	} {
		if !Valid(s) {
			t.Fatalf("%d: input not valid: %q", i, s)
		}
	}
	for i, s := range []string{
		"",
		"-",
		"--",
		"---",
		"----",
		"-----",
		"b-c-7-3-9",
		"x00000000-0000-0000-0000-000000000000",
		"00000000x-0000-0000-0000-000000000000",
		"00000000-x0000-0000-0000-000000000000",
		"00000000-0000x-0000-0000-000000000000",
		"00000000-0000-x0000-0000-000000000000",
		"00000000-0000-0000x-0000-000000000000",
		"00000000-0000-0000-x0000-000000000000",
		"00000000-0000-0000-0000-x000000000000",
		"000-0000-0000-0000-0000-000000000000",
		"000-0000-0000-0000-0000-000000000000-",
		"-000-0000-0000-0000-0000-000000000000",
	} {
		if Valid(s) {
			t.Fatalf("%d: false positive: %q", i, s)
		}
	}
}

func TestRace(t *testing.T) {
	done := make(chan bool)
	defer close(done)
	hammer := func() {
		var u string
		for i := 0; i < 1024; i++ {
			u = V4()
			if u == "" {
				panic("empty uuid")
			}
		}
		select {
		case <-done:
			return
		default:
		}
		u = u
	}
	for x := 0; x < 24; x++ {
		go hammer()
	}
	var uuids = []string{}
	for i := 0; i < N; i++ {
		uuids = append(uuids, V4())
	}
	time.Sleep(time.Second * 2)
	for i := 0; i < N; i++ {
		uuids = append(uuids, V4())
	}
	checkDistribution(t, uuids...)
}

func TestProbabilityDistribution(t *testing.T) {
	var uuids = []string{}
	for i := 0; i < N; i++ {
		uuids = append(uuids, V4())
	}
	checkDistribution(t, uuids...)
}

func checkDistribution(t *testing.T, uuids ...string) {
	t.Helper()
	const expected = 1.0 / 16.0 // ~0.0625
	var ctr [256]int
	for i := 0; i < N; i++ {
		u := []byte(V4())
		if len(u) != 36 {
			t.Fatal("bad length")
		}
		for _, c := range u {
			ctr[c]++
		}
	}
	if ctr['-'] != N*36/9 {
		t.Fatal("bad dash count")
	}
	ssq := 0.0
	for _, hex := range h {
		p := float64(ctr[hex]) / float64(N*(36-4))
		ssq += p * p
	}
	t.Log(ssq)
	have := math.Round(ssq * 1000)
	want := math.Round(expected * 1000)
	if have != want {
		t.Fatalf("non-uniform probability distribution: have %f, want %f", ssq, expected)
	}
}

func BenchmarkV4(b *testing.B) {
	for n := 0; n < b.N; n++ {
		_ = V4()
	}
}
func TestV4Parallel(t *testing.T) {
	t.Run("AB", func(t *testing.T) {
		t.Run("A", TestV4)
		t.Run("B", TestV4)
	})
}

func BenchmarkV4Parallel(b *testing.B) {
	b.Run("X2", func(t *testing.B) {
		t.Run("A", BenchmarkV4)
		t.Run("B", BenchmarkV4)
	})
	b.Run("X5", func(t *testing.B) {
		t.Run("A", BenchmarkV4)
		t.Run("B", BenchmarkV4)
		t.Run("C", BenchmarkV4)
		t.Run("D", BenchmarkV4)
		t.Run("E", BenchmarkV4)
	})
}