Skip to content
Permalink
Branch: master
Find file Copy path
Find file Copy path
Fetching contributors…
Cannot retrieve contributors at this time
120 lines (108 sloc) 2.75 KB
// Copyright 2013 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 strings_test
// Derived from bytes/compare_test.go.
// Benchmarks omitted since the underlying implementation is identical.
import (
"internal/testenv"
. "strings"
"testing"
"unsafe"
)
var compareTests = []struct {
a, b string
i int
}{
{"", "", 0},
{"a", "", 1},
{"", "a", -1},
{"abc", "abc", 0},
{"ab", "abc", -1},
{"abc", "ab", 1},
{"x", "ab", 1},
{"ab", "x", -1},
{"x", "a", 1},
{"b", "x", -1},
// test runtime·memeq's chunked implementation
{"abcdefgh", "abcdefgh", 0},
{"abcdefghi", "abcdefghi", 0},
{"abcdefghi", "abcdefghj", -1},
}
func TestCompare(t *testing.T) {
for _, tt := range compareTests {
cmp := Compare(tt.a, tt.b)
if cmp != tt.i {
t.Errorf(`Compare(%q, %q) = %v`, tt.a, tt.b, cmp)
}
}
}
func TestCompareIdenticalString(t *testing.T) {
var s = "Hello Gophers!"
if Compare(s, s) != 0 {
t.Error("s != s")
}
if Compare(s, s[:1]) != 1 {
t.Error("s > s[:1] failed")
}
}
func TestCompareStrings(t *testing.T) {
// unsafeString converts a []byte to a string with no allocation.
// The caller must not modify b while the result string is in use.
unsafeString := func(b []byte) string {
return *(*string)(unsafe.Pointer(&b))
}
lengths := make([]int, 0) // lengths to test in ascending order
for i := 0; i <= 128; i++ {
lengths = append(lengths, i)
}
lengths = append(lengths, 256, 512, 1024, 1333, 4095, 4096, 4097)
if !testing.Short() || testenv.Builder() != "" {
lengths = append(lengths, 65535, 65536, 65537, 99999)
}
n := lengths[len(lengths)-1]
a := make([]byte, n+1)
b := make([]byte, n+1)
lastLen := 0
for _, len := range lengths {
// randomish but deterministic data. No 0 or 255.
for i := 0; i < len; i++ {
a[i] = byte(1 + 31*i%254)
b[i] = byte(1 + 31*i%254)
}
// data past the end is different
for i := len; i <= n; i++ {
a[i] = 8
b[i] = 9
}
sa, sb := unsafeString(a), unsafeString(b)
cmp := Compare(sa[:len], sb[:len])
if cmp != 0 {
t.Errorf(`CompareIdentical(%d) = %d`, len, cmp)
}
if len > 0 {
cmp = Compare(sa[:len-1], sb[:len])
if cmp != -1 {
t.Errorf(`CompareAshorter(%d) = %d`, len, cmp)
}
cmp = Compare(sa[:len], sb[:len-1])
if cmp != 1 {
t.Errorf(`CompareBshorter(%d) = %d`, len, cmp)
}
}
for k := lastLen; k < len; k++ {
b[k] = a[k] - 1
cmp = Compare(unsafeString(a[:len]), unsafeString(b[:len]))
if cmp != 1 {
t.Errorf(`CompareAbigger(%d,%d) = %d`, len, k, cmp)
}
b[k] = a[k] + 1
cmp = Compare(unsafeString(a[:len]), unsafeString(b[:len]))
if cmp != -1 {
t.Errorf(`CompareBbigger(%d,%d) = %d`, len, k, cmp)
}
b[k] = a[k]
}
lastLen = len
}
}
You can’t perform that action at this time.