crc32_test.gno

 1package crc32
 2
 3import (
 4	"strings"
 5	"testing"
 6
 7	"gno.land/p/nt/uassert/v0"
 8)
 9
10// Known-answer tests against the published IEEE vectors.
11func TestChecksumKnownVectors(t *testing.T) {
12	cases := []struct {
13		in   string
14		want string
15	}{
16		{"", "00000000"},
17		{"a", "e8b7be43"},
18		{"abc", "352441c2"},
19		{"message digest", "20159d7f"},
20		{"abcdefghijklmnopqrstuvwxyz", "4c2750bd"},
21		{"123456789", "cbf43926"}, // the standard CRC check value
22	}
23	for _, c := range cases {
24		uassert.Equal(t, c.want, ChecksumHex(c.in))
25	}
26}
27
28// The classic "check" value: CRC-32/IEEE of "123456789" is 0xCBF43926.
29func TestStandardCheckValue(t *testing.T) {
30	uassert.Equal(t, uint32(0xCBF43926), Checksum("123456789"))
31}
32
33func TestHexIsZeroPadded(t *testing.T) {
34	uassert.Equal(t, "00000000", Hex(0))
35	uassert.Equal(t, "0000000f", Hex(15))
36	uassert.Equal(t, "ffffffff", Hex(0xFFFFFFFF))
37	uassert.Equal(t, 8, len(Hex(1)))
38}
39
40// A single flipped bit must change the checksum — the entire point.
41func TestDetectsSingleBitChange(t *testing.T) {
42	base := Checksum("hello world")
43	uassert.False(t, base == Checksum("hello worle"))
44	uassert.False(t, base == Checksum("Hello world"))
45}
46
47// Order matters: a CRC is not a sum.
48func TestOrderSensitive(t *testing.T) {
49	uassert.False(t, Checksum("ab") == Checksum("ba"))
50}
51
52func TestVerify(t *testing.T) {
53	uassert.True(t, Verify("abc", 0x352441C2))
54	uassert.False(t, Verify("abd", 0x352441C2))
55}
56
57// Chaining Update over chunks must equal one shot over the whole message —
58// this is why Update takes the raw register rather than a final value.
59func TestUpdateIsChunkable(t *testing.T) {
60	whole := Checksum("hello world")
61	crc := uint32(0xFFFFFFFF)
62	crc = Update(crc, ieeeTable, "hello ")
63	crc = Update(crc, ieeeTable, "world")
64	uassert.Equal(t, whole, Finalize(crc))
65}
66
67// Different polynomials must give different answers, and each be stable.
68func TestAlternatePolynomials(t *testing.T) {
69	c := MakeTable(Castagnoli)
70	k := MakeTable(Koopman)
71	a := ChecksumWith("123456789", c)
72	b := ChecksumWith("123456789", k)
73	uassert.False(t, a == Checksum("123456789"))
74	uassert.False(t, a == b)
75	uassert.Equal(t, a, ChecksumWith("123456789", c)) // stable
76}
77
78func TestSplit(t *testing.T) {
79	got := Split("a\nabc")
80	uassert.Equal(t, 2, len(got))
81	uassert.Equal(t, "e8b7be43", got[0])
82	uassert.Equal(t, "352441c2", got[1])
83}
84
85func TestLongInput(t *testing.T) {
86	s := strings.Repeat("gno", 1000)
87	uassert.Equal(t, 8, len(ChecksumHex(s)))
88	uassert.Equal(t, Checksum(s), Checksum(s))
89}