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  }
    50
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