libgo/go/strings/clone_test.go

   1 // Copyright 2021 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.ß
   4
   5 package strings_test
   6
   7 import (
   8         "reflect"
   9         "strings"
  10         "testing"
  11         "unsafe"
  12 )
  13
  14 var emptyString string
  15
  16 func TestClone(t *testing.T) {
  17         var cloneTests = []string{
  18                 "",
  19                 strings.Clone(""),
  20                 strings.Repeat("a", 42)[:0],
  21                 "short",
  22                 strings.Repeat("a", 42),
  23         }
  24         for _, input := range cloneTests {
  25                 clone := strings.Clone(input)
  26                 if clone != input {
  27                         t.Errorf("Clone(%q) = %q; want %q", input, clone, input)
  28                 }
  29
  30                 inputHeader := (*reflect.StringHeader)(unsafe.Pointer(&input))
  31                 cloneHeader := (*reflect.StringHeader)(unsafe.Pointer(&clone))
  32                 if len(input) != 0 && cloneHeader.Data == inputHeader.Data {
  33                         t.Errorf("Clone(%q) return value should not reference inputs backing memory.", input)
  34                 }
  35
  36                 emptyHeader := (*reflect.StringHeader)(unsafe.Pointer(&emptyString))
  37                 if len(input) == 0 && cloneHeader.Data != emptyHeader.Data {
  38                         t.Errorf("Clone(%#v) return value should be equal to empty string.", inputHeader)
  39                 }
  40         }
  41 }
  42
  43 func BenchmarkClone(b *testing.B) {
  44         var str = strings.Repeat("a", 42)
  45         b.ReportAllocs()
  46         for i := 0; i < b.N; i++ {
  47                 stringSink = strings.Clone(str)
  48         }
  49 }