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mirror of https://github.com/octoleo/restic.git synced 2024-12-23 11:28:54 +00:00
restic/internal/backend/test/tests.go
2022-12-03 18:56:55 +01:00

898 lines
22 KiB
Go

package test
import (
"bytes"
"context"
"fmt"
"io"
"math/rand"
"os"
"reflect"
"sort"
"testing"
"time"
"github.com/minio/sha256-simd"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/restic"
"github.com/restic/restic/internal/test"
"github.com/restic/restic/internal/backend"
)
func seedRand(t testing.TB) {
seed := time.Now().UnixNano()
rand.Seed(seed)
t.Logf("rand initialized with seed %d", seed)
}
func beTest(ctx context.Context, be restic.Backend, h restic.Handle) (bool, error) {
_, err := be.Stat(ctx, h)
if err != nil && be.IsNotExist(err) {
return false, nil
}
return err == nil, err
}
// TestCreateWithConfig tests that creating a backend in a location which already
// has a config file fails.
func (s *Suite) TestCreateWithConfig(t *testing.T) {
b := s.open(t)
defer s.close(t, b)
// remove a config if present
cfgHandle := restic.Handle{Type: restic.ConfigFile}
cfgPresent, err := beTest(context.TODO(), b, cfgHandle)
if err != nil {
t.Fatalf("unable to test for config: %+v", err)
}
if cfgPresent {
remove(t, b, cfgHandle)
}
// save a config
store(t, b, restic.ConfigFile, []byte("test config"))
// now create the backend again, this must fail
_, err = s.Create(s.Config)
if err == nil {
t.Fatalf("expected error not found for creating a backend with an existing config file")
}
// remove config
err = b.Remove(context.TODO(), restic.Handle{Type: restic.ConfigFile, Name: ""})
if err != nil {
t.Fatalf("unexpected error removing config: %+v", err)
}
}
// TestLocation tests that a location string is returned.
func (s *Suite) TestLocation(t *testing.T) {
b := s.open(t)
defer s.close(t, b)
l := b.Location()
if l == "" {
t.Fatalf("invalid location string %q", l)
}
}
// TestConfig saves and loads a config from the backend.
func (s *Suite) TestConfig(t *testing.T) {
b := s.open(t)
defer s.close(t, b)
var testString = "Config"
// create config and read it back
_, err := backend.LoadAll(context.TODO(), nil, b, restic.Handle{Type: restic.ConfigFile})
if err == nil {
t.Fatalf("did not get expected error for non-existing config")
}
test.Assert(t, b.IsNotExist(err), "IsNotExist() did not recognize error from LoadAll(): %v", err)
err = b.Save(context.TODO(), restic.Handle{Type: restic.ConfigFile}, restic.NewByteReader([]byte(testString), b.Hasher()))
if err != nil {
t.Fatalf("Save() error: %+v", err)
}
// try accessing the config with different names, should all return the
// same config
for _, name := range []string{"", "foo", "bar", "0000000000000000000000000000000000000000000000000000000000000000"} {
h := restic.Handle{Type: restic.ConfigFile, Name: name}
buf, err := backend.LoadAll(context.TODO(), nil, b, h)
if err != nil {
t.Fatalf("unable to read config with name %q: %+v", name, err)
}
if string(buf) != testString {
t.Fatalf("wrong data returned, want %q, got %q", testString, string(buf))
}
}
// remove the config
remove(t, b, restic.Handle{Type: restic.ConfigFile})
}
// TestLoad tests the backend's Load function.
func (s *Suite) TestLoad(t *testing.T) {
seedRand(t)
b := s.open(t)
defer s.close(t, b)
noop := func(rd io.Reader) error {
return nil
}
err := b.Load(context.TODO(), restic.Handle{}, 0, 0, noop)
if err == nil {
t.Fatalf("Load() did not return an error for invalid handle")
}
test.Assert(t, !b.IsNotExist(err), "IsNotExist() should not accept an invalid handle error: %v", err)
err = testLoad(b, restic.Handle{Type: restic.PackFile, Name: "foobar"}, 0, 0)
if err == nil {
t.Fatalf("Load() did not return an error for non-existing blob")
}
test.Assert(t, b.IsNotExist(err), "IsNotExist() did not recognize non-existing blob: %v", err)
length := rand.Intn(1<<24) + 2000
data := test.Random(23, length)
id := restic.Hash(data)
handle := restic.Handle{Type: restic.PackFile, Name: id.String()}
err = b.Save(context.TODO(), handle, restic.NewByteReader(data, b.Hasher()))
if err != nil {
t.Fatalf("Save() error: %+v", err)
}
t.Logf("saved %d bytes as %v", length, handle)
err = b.Load(context.TODO(), handle, 100, -1, noop)
if err == nil {
t.Fatalf("Load() returned no error for negative offset!")
}
err = b.Load(context.TODO(), handle, 0, 0, func(rd io.Reader) error {
_, err := io.Copy(io.Discard, rd)
if err != nil {
t.Fatal(err)
}
return errors.Errorf("deliberate error")
})
if err == nil {
t.Fatalf("Load() did not propagate consumer error!")
}
if err.Error() != "deliberate error" {
t.Fatalf("Load() did not correctly propagate consumer error!")
}
loadTests := 50
if s.MinimalData {
loadTests = 10
}
for i := 0; i < loadTests; i++ {
l := rand.Intn(length + 2000)
o := rand.Intn(length + 2000)
d := data
if o < len(d) {
d = d[o:]
} else {
t.Logf("offset == length, skipping test")
continue
}
getlen := l
if l >= len(d) && rand.Float32() >= 0.5 {
getlen = 0
}
if l > 0 && l < len(d) {
d = d[:l]
}
var buf []byte
err := b.Load(context.TODO(), handle, getlen, int64(o), func(rd io.Reader) (ierr error) {
buf, ierr = io.ReadAll(rd)
return ierr
})
if err != nil {
t.Logf("Load, l %v, o %v, len(d) %v, getlen %v", l, o, len(d), getlen)
t.Errorf("Load(%d, %d) returned unexpected error: %+v", l, o, err)
continue
}
if l == 0 && len(buf) != len(d) {
t.Logf("Load, l %v, o %v, len(d) %v, getlen %v", l, o, len(d), getlen)
t.Errorf("Load(%d, %d) wrong number of bytes read: want %d, got %d", l, o, len(d), len(buf))
continue
}
if l > 0 && l <= len(d) && len(buf) != l {
t.Logf("Load, l %v, o %v, len(d) %v, getlen %v", l, o, len(d), getlen)
t.Errorf("Load(%d, %d) wrong number of bytes read: want %d, got %d", l, o, l, len(buf))
continue
}
if l > len(d) && len(buf) != len(d) {
t.Logf("Load, l %v, o %v, len(d) %v, getlen %v", l, o, len(d), getlen)
t.Errorf("Load(%d, %d) wrong number of bytes read for overlong read: want %d, got %d", l, o, l, len(buf))
continue
}
if !bytes.Equal(buf, d) {
t.Logf("Load, l %v, o %v, len(d) %v, getlen %v", l, o, len(d), getlen)
t.Errorf("Load(%d, %d) returned wrong bytes", l, o)
continue
}
}
test.OK(t, b.Remove(context.TODO(), handle))
}
// TestList makes sure that the backend implements List() pagination correctly.
func (s *Suite) TestList(t *testing.T) {
seedRand(t)
numTestFiles := rand.Intn(20) + 20
b := s.open(t)
defer s.close(t, b)
// Check that the backend is empty to start with
var found []string
err := b.List(context.TODO(), restic.PackFile, func(fi restic.FileInfo) error {
found = append(found, fi.Name)
return nil
})
if err != nil {
t.Fatalf("List returned error %v", err)
}
if found != nil {
t.Fatalf("backend not empty at start of test - contains: %v", found)
}
list1 := make(map[restic.ID]int64)
for i := 0; i < numTestFiles; i++ {
data := test.Random(rand.Int(), rand.Intn(100)+55)
id := restic.Hash(data)
h := restic.Handle{Type: restic.PackFile, Name: id.String()}
err := b.Save(context.TODO(), h, restic.NewByteReader(data, b.Hasher()))
if err != nil {
t.Fatal(err)
}
list1[id] = int64(len(data))
}
t.Logf("wrote %v files", len(list1))
var tests = []struct {
maxItems int
}{
{11}, {23}, {numTestFiles}, {numTestFiles + 10}, {numTestFiles + 1123},
}
for _, test := range tests {
t.Run(fmt.Sprintf("max-%v", test.maxItems), func(t *testing.T) {
list2 := make(map[restic.ID]int64)
type setter interface {
SetListMaxItems(int)
}
if s, ok := b.(setter); ok {
t.Logf("setting max list items to %d", test.maxItems)
s.SetListMaxItems(test.maxItems)
}
err := b.List(context.TODO(), restic.PackFile, func(fi restic.FileInfo) error {
id, err := restic.ParseID(fi.Name)
if err != nil {
t.Fatal(err)
}
list2[id] = fi.Size
return nil
})
if err != nil {
t.Fatalf("List returned error %v", err)
}
t.Logf("loaded %v IDs from backend", len(list2))
for id, size := range list1 {
size2, ok := list2[id]
if !ok {
t.Errorf("id %v not returned by List()", id.Str())
}
if size != size2 {
t.Errorf("wrong size for id %v returned: want %v, got %v", id.Str(), size, size2)
}
}
for id := range list2 {
_, ok := list1[id]
if !ok {
t.Errorf("extra id %v returned by List()", id.Str())
}
}
})
}
t.Logf("remove %d files", numTestFiles)
handles := make([]restic.Handle, 0, len(list1))
for id := range list1 {
handles = append(handles, restic.Handle{Type: restic.PackFile, Name: id.String()})
}
err = s.delayedRemove(t, b, handles...)
if err != nil {
t.Fatal(err)
}
}
// TestListCancel tests that the context is respected and the error is returned by List.
func (s *Suite) TestListCancel(t *testing.T) {
seedRand(t)
numTestFiles := 5
b := s.open(t)
defer s.close(t, b)
testFiles := make([]restic.Handle, 0, numTestFiles)
for i := 0; i < numTestFiles; i++ {
data := []byte(fmt.Sprintf("random test blob %v", i))
id := restic.Hash(data)
h := restic.Handle{Type: restic.PackFile, Name: id.String()}
err := b.Save(context.TODO(), h, restic.NewByteReader(data, b.Hasher()))
if err != nil {
t.Fatal(err)
}
testFiles = append(testFiles, h)
}
t.Run("Cancelled", func(t *testing.T) {
ctx, cancel := context.WithCancel(context.TODO())
cancel()
// pass in a cancelled context
err := b.List(ctx, restic.PackFile, func(fi restic.FileInfo) error {
t.Errorf("got FileInfo %v for cancelled context", fi)
return nil
})
if !errors.Is(err, context.Canceled) {
t.Fatalf("expected error not found, want %v, got %v", context.Canceled, err)
}
})
t.Run("First", func(t *testing.T) {
ctx, cancel := context.WithCancel(context.TODO())
defer cancel()
i := 0
err := b.List(ctx, restic.PackFile, func(fi restic.FileInfo) error {
i++
// cancel the context on the first file
if i == 1 {
cancel()
}
return nil
})
if !errors.Is(err, context.Canceled) {
t.Fatalf("expected error not found, want %v, got %v", context.Canceled, err)
}
if i != 1 {
t.Fatalf("wrong number of files returned by List, want %v, got %v", 1, i)
}
})
t.Run("Last", func(t *testing.T) {
ctx, cancel := context.WithCancel(context.TODO())
defer cancel()
i := 0
err := b.List(ctx, restic.PackFile, func(fi restic.FileInfo) error {
// cancel the context at the last file
i++
if i == numTestFiles {
cancel()
}
return nil
})
if !errors.Is(err, context.Canceled) {
t.Fatalf("expected error not found, want %v, got %v", context.Canceled, err)
}
if i != numTestFiles {
t.Fatalf("wrong number of files returned by List, want %v, got %v", numTestFiles, i)
}
})
t.Run("Timeout", func(t *testing.T) {
// rather large timeout, let's try to get at least one item
timeout := time.Second
ctxTimeout, cancel := context.WithTimeout(context.TODO(), timeout)
defer cancel()
i := 0
// pass in a context with a timeout
err := b.List(ctxTimeout, restic.PackFile, func(fi restic.FileInfo) error {
i++
// wait until the context is cancelled
<-ctxTimeout.Done()
return nil
})
if !errors.Is(err, context.DeadlineExceeded) {
t.Fatalf("expected error not found, want %#v, got %#v", context.DeadlineExceeded, err)
}
if i > 2 {
t.Fatalf("wrong number of files returned by List, want <= 2, got %v", i)
}
})
err := s.delayedRemove(t, b, testFiles...)
if err != nil {
t.Fatal(err)
}
}
type errorCloser struct {
io.ReadSeeker
l int64
t testing.TB
h []byte
}
func (ec errorCloser) Close() error {
ec.t.Error("forbidden method close was called")
return errors.New("forbidden method close was called")
}
func (ec errorCloser) Length() int64 {
return ec.l
}
func (ec errorCloser) Hash() []byte {
return ec.h
}
func (ec errorCloser) Rewind() error {
_, err := ec.ReadSeeker.Seek(0, io.SeekStart)
return err
}
// TestSave tests saving data in the backend.
func (s *Suite) TestSave(t *testing.T) {
seedRand(t)
b := s.open(t)
defer s.close(t, b)
var id restic.ID
saveTests := 10
if s.MinimalData {
saveTests = 2
}
for i := 0; i < saveTests; i++ {
length := rand.Intn(1<<23) + 200000
data := test.Random(23, length)
id = sha256.Sum256(data)
h := restic.Handle{
Type: restic.PackFile,
Name: id.String(),
}
err := b.Save(context.TODO(), h, restic.NewByteReader(data, b.Hasher()))
test.OK(t, err)
buf, err := backend.LoadAll(context.TODO(), nil, b, h)
test.OK(t, err)
if len(buf) != len(data) {
t.Fatalf("number of bytes does not match, want %v, got %v", len(data), len(buf))
}
if !bytes.Equal(buf, data) {
t.Fatalf("data not equal")
}
fi, err := b.Stat(context.TODO(), h)
test.OK(t, err)
if fi.Name != h.Name {
t.Errorf("Stat() returned wrong name, want %q, got %q", h.Name, fi.Name)
}
if fi.Size != int64(len(data)) {
t.Errorf("Stat() returned different size, want %q, got %d", len(data), fi.Size)
}
err = b.Remove(context.TODO(), h)
if err != nil {
t.Fatalf("error removing item: %+v", err)
}
}
// test saving from a tempfile
tmpfile, err := os.CreateTemp("", "restic-backend-save-test-")
if err != nil {
t.Fatal(err)
}
length := rand.Intn(1<<23) + 200000
data := test.Random(23, length)
id = sha256.Sum256(data)
if _, err = tmpfile.Write(data); err != nil {
t.Fatal(err)
}
if _, err = tmpfile.Seek(0, io.SeekStart); err != nil {
t.Fatal(err)
}
h := restic.Handle{Type: restic.PackFile, Name: id.String()}
// wrap the tempfile in an errorCloser, so we can detect if the backend
// closes the reader
var beHash []byte
if b.Hasher() != nil {
beHasher := b.Hasher()
// must never fail according to interface
_, err := beHasher.Write(data)
if err != nil {
panic(err)
}
beHash = beHasher.Sum(nil)
}
err = b.Save(context.TODO(), h, errorCloser{
t: t,
l: int64(length),
ReadSeeker: tmpfile,
h: beHash,
})
if err != nil {
t.Fatal(err)
}
err = s.delayedRemove(t, b, h)
if err != nil {
t.Fatalf("error removing item: %+v", err)
}
if err = tmpfile.Close(); err != nil {
t.Fatal(err)
}
if err = os.Remove(tmpfile.Name()); err != nil {
t.Fatal(err)
}
}
type incompleteByteReader struct {
restic.ByteReader
}
func (r *incompleteByteReader) Length() int64 {
return r.ByteReader.Length() + 42
}
// TestSaveError tests saving data in the backend.
func (s *Suite) TestSaveError(t *testing.T) {
seedRand(t)
b := s.open(t)
defer func() {
// rclone will report an error when closing the backend. We have to ignore it
// otherwise this test will always fail
_ = b.Close()
}()
length := rand.Intn(1<<23) + 200000
data := test.Random(24, length)
var id restic.ID
copy(id[:], data)
// test that incomplete uploads fail
h := restic.Handle{Type: restic.PackFile, Name: id.String()}
err := b.Save(context.TODO(), h, &incompleteByteReader{ByteReader: *restic.NewByteReader(data, b.Hasher())})
// try to delete possible leftovers
_ = s.delayedRemove(t, b, h)
if err == nil {
t.Fatal("incomplete upload did not fail")
}
}
type wrongByteReader struct {
restic.ByteReader
}
func (b *wrongByteReader) Hash() []byte {
h := b.ByteReader.Hash()
modHash := make([]byte, len(h))
copy(modHash, h)
// flip a bit in the hash
modHash[0] ^= 0x01
return modHash
}
// TestSaveWrongHash tests that uploads with a wrong hash fail
func (s *Suite) TestSaveWrongHash(t *testing.T) {
seedRand(t)
b := s.open(t)
defer s.close(t, b)
// nothing to do if the backend doesn't support external hashes
if b.Hasher() == nil {
return
}
length := rand.Intn(1<<23) + 200000
data := test.Random(25, length)
var id restic.ID
copy(id[:], data)
// test that upload with hash mismatch fails
h := restic.Handle{Type: restic.PackFile, Name: id.String()}
err := b.Save(context.TODO(), h, &wrongByteReader{ByteReader: *restic.NewByteReader(data, b.Hasher())})
exists, err2 := beTest(context.TODO(), b, h)
if err2 != nil {
t.Fatal(err2)
}
_ = s.delayedRemove(t, b, h)
if err == nil {
t.Fatal("upload with wrong hash did not fail")
}
t.Logf("%v", err)
if exists {
t.Fatal("Backend returned an error but stored the file anyways")
}
}
var testStrings = []struct {
id string
data string
}{
{"c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2", "foobar"},
{"248d6a61d20638b8e5c026930c3e6039a33ce45964ff2167f6ecedd419db06c1", "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"},
{"cc5d46bdb4991c6eae3eb739c9c8a7a46fe9654fab79c47b4fe48383b5b25e1c", "foo/bar"},
{"4e54d2c721cbdb730f01b10b62dec622962b36966ec685880effa63d71c808f2", "foo/../../baz"},
}
func store(t testing.TB, b restic.Backend, tpe restic.FileType, data []byte) restic.Handle {
id := restic.Hash(data)
h := restic.Handle{Name: id.String(), Type: tpe}
err := b.Save(context.TODO(), h, restic.NewByteReader([]byte(data), b.Hasher()))
test.OK(t, err)
return h
}
// testLoad loads a blob (but discards its contents).
func testLoad(b restic.Backend, h restic.Handle, length int, offset int64) error {
return b.Load(context.TODO(), h, 0, 0, func(rd io.Reader) (ierr error) {
_, ierr = io.Copy(io.Discard, rd)
return ierr
})
}
func (s *Suite) delayedRemove(t testing.TB, be restic.Backend, handles ...restic.Handle) error {
// Some backend (swift, I'm looking at you) may implement delayed
// removal of data. Let's wait a bit if this happens.
for _, h := range handles {
err := be.Remove(context.TODO(), h)
if s.ErrorHandler != nil {
err = s.ErrorHandler(t, be, err)
}
if err != nil {
return err
}
}
for _, h := range handles {
start := time.Now()
attempt := 0
var found bool
var err error
for time.Since(start) <= s.WaitForDelayedRemoval {
found, err = beTest(context.TODO(), be, h)
if s.ErrorHandler != nil {
err = s.ErrorHandler(t, be, err)
}
if err != nil {
return err
}
if !found {
break
}
time.Sleep(2 * time.Second)
attempt++
}
if found {
t.Fatalf("removed blob %v still present after %v (%d attempts)", h, time.Since(start), attempt)
}
}
return nil
}
func delayedList(t testing.TB, b restic.Backend, tpe restic.FileType, max int, maxwait time.Duration) restic.IDs {
list := restic.NewIDSet()
start := time.Now()
for i := 0; i < max; i++ {
err := b.List(context.TODO(), tpe, func(fi restic.FileInfo) error {
id := restic.TestParseID(fi.Name)
list.Insert(id)
return nil
})
if err != nil {
t.Fatal(err)
}
if len(list) < max && time.Since(start) < maxwait {
time.Sleep(500 * time.Millisecond)
}
}
return list.List()
}
// TestBackend tests all functions of the backend.
func (s *Suite) TestBackend(t *testing.T) {
b := s.open(t)
defer s.close(t, b)
test.Assert(t, !b.IsNotExist(nil), "IsNotExist() recognized nil error")
for _, tpe := range []restic.FileType{
restic.PackFile, restic.KeyFile, restic.LockFile,
restic.SnapshotFile, restic.IndexFile,
} {
// detect non-existing files
for _, ts := range testStrings {
id, err := restic.ParseID(ts.id)
test.OK(t, err)
// test if blob is already in repository
h := restic.Handle{Type: tpe, Name: id.String()}
ret, err := beTest(context.TODO(), b, h)
test.OK(t, err)
test.Assert(t, !ret, "blob was found to exist before creating")
// try to stat a not existing blob
_, err = b.Stat(context.TODO(), h)
test.Assert(t, err != nil, "blob data could be extracted before creation")
test.Assert(t, b.IsNotExist(err), "IsNotExist() did not recognize Stat() error: %v", err)
// try to read not existing blob
err = testLoad(b, h, 0, 0)
test.Assert(t, err != nil, "blob could be read before creation")
test.Assert(t, b.IsNotExist(err), "IsNotExist() did not recognize Load() error: %v", err)
// try to get string out, should fail
ret, err = beTest(context.TODO(), b, h)
test.OK(t, err)
test.Assert(t, !ret, "id %q was found (but should not have)", ts.id)
}
// add files
for _, ts := range testStrings {
store(t, b, tpe, []byte(ts.data))
// test Load()
h := restic.Handle{Type: tpe, Name: ts.id}
buf, err := backend.LoadAll(context.TODO(), nil, b, h)
test.OK(t, err)
test.Equals(t, ts.data, string(buf))
// try to read it out with an offset and a length
start := 1
end := len(ts.data) - 2
length := end - start
buf2 := make([]byte, length)
var n int
err = b.Load(context.TODO(), h, len(buf2), int64(start), func(rd io.Reader) (ierr error) {
n, ierr = io.ReadFull(rd, buf2)
return ierr
})
test.OK(t, err)
test.OK(t, err)
test.Equals(t, len(buf2), n)
test.Equals(t, ts.data[start:end], string(buf2))
}
// test adding the first file again
ts := testStrings[0]
h := restic.Handle{Type: tpe, Name: ts.id}
// remove and recreate
err := s.delayedRemove(t, b, h)
test.OK(t, err)
// test that the blob is gone
ok, err := beTest(context.TODO(), b, h)
test.OK(t, err)
test.Assert(t, !ok, "removed blob still present")
// create blob
err = b.Save(context.TODO(), h, restic.NewByteReader([]byte(ts.data), b.Hasher()))
test.OK(t, err)
// list items
IDs := restic.IDs{}
for _, ts := range testStrings {
id, err := restic.ParseID(ts.id)
test.OK(t, err)
IDs = append(IDs, id)
}
list := delayedList(t, b, tpe, len(IDs), s.WaitForDelayedRemoval)
if len(IDs) != len(list) {
t.Fatalf("wrong number of IDs returned: want %d, got %d", len(IDs), len(list))
}
sort.Sort(IDs)
sort.Sort(list)
if !reflect.DeepEqual(IDs, list) {
t.Fatalf("lists aren't equal, want:\n %v\n got:\n%v\n", IDs, list)
}
var handles []restic.Handle
for _, ts := range testStrings {
id, err := restic.ParseID(ts.id)
test.OK(t, err)
h := restic.Handle{Type: tpe, Name: id.String()}
found, err := beTest(context.TODO(), b, h)
test.OK(t, err)
test.Assert(t, found, fmt.Sprintf("id %v/%q not found", tpe, id))
handles = append(handles, h)
}
test.OK(t, s.delayedRemove(t, b, handles...))
}
}
// TestZZZDelete tests the Delete function. The name ensures that this test is executed last.
func (s *Suite) TestZZZDelete(t *testing.T) {
if !test.TestCleanupTempDirs {
t.Skipf("not removing backend, TestCleanupTempDirs is false")
}
b := s.open(t)
defer s.close(t, b)
err := b.Delete(context.TODO())
if err != nil {
t.Fatalf("error deleting backend: %+v", err)
}
}