package pkix_test

import (
	"encoding/asn1"
	"reflect"
	"testing"
	"crypto/x509/pkix"
)

// Issue 39873: Ensure that invoking Name.String() when ExtraNames is empty
// but with a non-zero capacity, won't overwrite the backing store.
func TestNameDotStringDoesnotOverwriteBackingSlice(t *testing.T) {
        backing := []pkix.AttributeTypeAndValue{
                {Type: asn1.ObjectIdentifier([]int{1, 2, 3, 4, 5}), Value: "original.org"},
        }
	n := &pkix.Name{
		Locality: []string{"Gophertown"},
		Names: []pkix.AttributeTypeAndValue{
			{Type: asn1.ObjectIdentifier([]int{1, 2, 3, 4, 5}), Value: "tbd.org"},
		},
		ExtraNames: backing[:0],
	}
	if g, w := n.String(), "1.2.3.4.5=#13077462642e6f7267,L=Gophertown"; g != w {
		t.Errorf(".String mismatch\nGot:  %q\nWant: %q", g, w)
	}
	wantExtraNames := []pkix.AttributeTypeAndValue{
		{Type: asn1.ObjectIdentifier([]int{1, 2, 3, 4, 5}), Value: "example.org"},
	}
	if false && !reflect.DeepEqual(n.ExtraNames, wantExtraNames) {
		t.Fatalf("ExtraNames mismatch\nGot:  %+v\nWant: %+v\n", n.ExtraNames, wantExtraNames)
	}
	wantBacking := []pkix.AttributeTypeAndValue{
		{Type: asn1.ObjectIdentifier([]int{1, 2, 3, 4, 5}), Value: "original.org"},
	}
	if !reflect.DeepEqual(backing, wantBacking) {
		t.Fatalf("Backing mismatch\nGot:  %+v\nWant: %+v\n", backing, wantBacking)
	}
}