[#139] test: Add test storage implementation

This aims to reduce the usage of chmod hackery to induce or simulate
OS-related failures.

Signed-off-by: Alejandro Lopez <a.lopez@yadro.com>

cmd/frostfs-lens/internal/writecache/root.go

@@ -1,6 +1,8 @@
 package writecache
 
 import (
+	"os"
+
 	common "git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-lens/internal"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/writecache"
 	"github.com/spf13/cobra"
@@ -24,7 +26,7 @@ func init() {
 }
 
 func openWC(cmd *cobra.Command) *bbolt.DB {
-	db, err := writecache.OpenDB(vPath, true)
+	db, err := writecache.OpenDB(vPath, true, os.OpenFile)
 	common.ExitOnErr(cmd, common.Errf("could not open write-cache db: %w", err))
 
 	return db

pkg/local_object_storage/blobstor/blobovniczatree/exists_test.go

@@ -50,7 +50,6 @@ func TestExistsInvalidStorageID(t *testing.T) {
 	})
 
 	t.Run("invalid storage id", func(t *testing.T) {
-		// "0/X/Y" <-> "1/X/Y"
 		storageID := slice.Copy(putRes.StorageID)
 		storageID[0] = '9'
 		badDir := filepath.Join(dir, "9")

pkg/local_object_storage/blobstor/blobstor_test.go

@@ -1,7 +1,6 @@
 package blobstor
 
 import (
-	"os"
 	"path/filepath"
 	"testing"
 
@@ -9,32 +8,37 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/blobovniczatree"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/fstree"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/teststore"
 	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
 	"github.com/stretchr/testify/require"
 )
 
-const blobovniczaDir = "blobovniczas"
-
-func defaultStorages(p string, smallSizeLimit uint64) []SubStorage {
+func defaultTestStorages(p string, smallSizeLimit uint64) ([]SubStorage, *teststore.TestStore, *teststore.TestStore) {
+	smallFileStorage := teststore.New(teststore.WithSubstorage(blobovniczatree.NewBlobovniczaTree(
+		blobovniczatree.WithRootPath(filepath.Join(p, "blobovniczas")),
+		blobovniczatree.WithBlobovniczaShallowWidth(1)), // default width is 16, slow init
+	))
+	largeFileStorage := teststore.New(teststore.WithSubstorage(fstree.New(fstree.WithPath(p))))
 	return []SubStorage{
 		{
-			Storage: blobovniczatree.NewBlobovniczaTree(
-				blobovniczatree.WithRootPath(filepath.Join(p, "blobovniczas")),
-				blobovniczatree.WithBlobovniczaShallowWidth(1)), // default width is 16, slow init
+			Storage: smallFileStorage,
 			Policy: func(_ *objectSDK.Object, data []byte) bool {
 				return uint64(len(data)) <= smallSizeLimit
 			},
 		},
 		{
-			Storage: fstree.New(fstree.WithPath(p)),
+			Storage: largeFileStorage,
 		},
-	}
+	}, smallFileStorage, largeFileStorage
+}
+
+func defaultStorages(p string, smallSizeLimit uint64) []SubStorage {
+	storages, _, _ := defaultTestStorages(p, smallSizeLimit)
+	return storages
 }
 
 func TestCompression(t *testing.T) {
-	dir, err := os.MkdirTemp("", "frostfs*")
-	require.NoError(t, err)
-	t.Cleanup(func() { _ = os.RemoveAll(dir) })
+	dir := t.TempDir()
 
 	const (
 		smallSizeLimit = 512
@@ -70,7 +74,7 @@ func TestCompression(t *testing.T) {
 	testPut := func(t *testing.T, b *BlobStor, i int) {
 		var prm common.PutPrm
 		prm.Object = smallObj[i]
-		_, err = b.Put(prm)
+		_, err := b.Put(prm)
 		require.NoError(t, err)
 
 		prm = common.PutPrm{}
@@ -102,9 +106,7 @@ func TestCompression(t *testing.T) {
 func TestBlobstor_needsCompression(t *testing.T) {
 	const smallSizeLimit = 512
 	newBlobStor := func(t *testing.T, compress bool, ct ...string) *BlobStor {
-		dir, err := os.MkdirTemp("", "frostfs*")
-		require.NoError(t, err)
-		t.Cleanup(func() { _ = os.RemoveAll(dir) })
+		dir := t.TempDir()
 
 		bs := New(
 			WithCompressObjects(compress),

pkg/local_object_storage/blobstor/exists_test.go

@@ -2,11 +2,11 @@ package blobstor
 
 import (
 	"os"
-	"path/filepath"
 	"testing"
 
 	objectCore "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/teststore"
 	cidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id/test"
 	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
 	oidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id/test"
@@ -20,8 +20,10 @@ func TestExists(t *testing.T) {
 
 	const smallSizeLimit = 512
 
-	b := New(
-		WithStorages(defaultStorages(dir, smallSizeLimit)))
+	storages, _, largeFileStorage := defaultTestStorages(dir, smallSizeLimit)
+
+	b := New(WithStorages(storages))
+
 	require.NoError(t, b.Open(false))
 	require.NoError(t, b.Init())
 
@@ -33,7 +35,7 @@ func TestExists(t *testing.T) {
 	for i := range objects {
 		var prm common.PutPrm
 		prm.Object = objects[i]
-		_, err = b.Put(prm)
+		_, err := b.Put(prm)
 		require.NoError(t, err)
 	}
 
@@ -51,20 +53,10 @@ func TestExists(t *testing.T) {
 	require.NoError(t, err)
 	require.False(t, res.Exists)
 
-	t.Run("corrupt direcrory", func(t *testing.T) {
-		var bigDir string
-		de, err := os.ReadDir(dir)
-		require.NoError(t, err)
-		for i := range de {
-			if de[i].Name() != blobovniczaDir {
-				bigDir = filepath.Join(dir, de[i].Name())
-				break
-			}
-		}
-		require.NotEmpty(t, bigDir)
-
-		require.NoError(t, os.Chmod(dir, 0))
-		t.Cleanup(func() { require.NoError(t, os.Chmod(dir, 0777)) })
+	t.Run("corrupt directory", func(t *testing.T) {
+		largeFileStorage.SetOption(teststore.WithExists(func(common.ExistsPrm) (common.ExistsRes, error) {
+			return common.ExistsRes{}, teststore.ErrDiskExploded
+		}))
 
 		// Object exists, first error is logged.
 		prm.Address = objectCore.AddressOf(objects[0])
@@ -76,6 +68,7 @@ func TestExists(t *testing.T) {
 		prm.Address = objectCore.AddressOf(objects[1])
 		_, err = b.Exists(prm)
 		require.Error(t, err)
+		require.ErrorIs(t, err, teststore.ErrDiskExploded)
 	})
 }
 

pkg/local_object_storage/blobstor/generic_test.go

@@ -1,23 +1,16 @@
 package blobstor
 
 import (
-	"os"
-	"path/filepath"
-	"strconv"
 	"testing"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/storagetest"
 )
 
 func TestGeneric(t *testing.T) {
-	defer func() { _ = os.RemoveAll(t.Name()) }()
 
-	var n int
 	newMetabase := func(t *testing.T) storagetest.Component {
-		n++
-		dir := filepath.Join(t.Name(), strconv.Itoa(n))
 		return New(
-			WithStorages(defaultStorages(dir, 128)))
+			WithStorages(defaultStorages(t.TempDir(), 128)))
 	}
 
 	storagetest.TestAll(t, newMetabase)

pkg/local_object_storage/blobstor/teststore/option.go

@@ -0,0 +1,74 @@
+package teststore
+
+import (
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/compression"
+)
+
+type cfg struct {
+	st        common.Storage
+	overrides struct {
+		Open  func(readOnly bool) error
+		Init  func() error
+		Close func() error
+
+		Type               func() string
+		Path               func() string
+		SetCompressor      func(cc *compression.Config)
+		SetReportErrorFunc func(f func(string, error))
+
+		Get      func(common.GetPrm) (common.GetRes, error)
+		GetRange func(common.GetRangePrm) (common.GetRangeRes, error)
+		Exists   func(common.ExistsPrm) (common.ExistsRes, error)
+		Put      func(common.PutPrm) (common.PutRes, error)
+		Delete   func(common.DeletePrm) (common.DeleteRes, error)
+		Iterate  func(common.IteratePrm) (common.IterateRes, error)
+	}
+}
+
+type Option func(*cfg)
+
+func WithSubstorage(st common.Storage) Option {
+	return func(c *cfg) {
+		c.st = st
+	}
+}
+
+func WithOpen(f func(bool) error) Option { return func(c *cfg) { c.overrides.Open = f } }
+func WithInit(f func() error) Option     { return func(c *cfg) { c.overrides.Init = f } }
+func WithClose(f func() error) Option    { return func(c *cfg) { c.overrides.Close = f } }
+
+func WithType(f func() string) Option { return func(c *cfg) { c.overrides.Type = f } }
+func WithPath(f func() string) Option { return func(c *cfg) { c.overrides.Path = f } }
+
+func WithSetCompressor(f func(*compression.Config)) Option {
+	return func(c *cfg) { c.overrides.SetCompressor = f }
+}
+
+func WithReportErrorFunc(f func(func(string, error))) Option {
+	return func(c *cfg) { c.overrides.SetReportErrorFunc = f }
+}
+
+func WithGet(f func(common.GetPrm) (common.GetRes, error)) Option {
+	return func(c *cfg) { c.overrides.Get = f }
+}
+
+func WithGetRange(f func(common.GetRangePrm) (common.GetRangeRes, error)) Option {
+	return func(c *cfg) { c.overrides.GetRange = f }
+}
+
+func WithExists(f func(common.ExistsPrm) (common.ExistsRes, error)) Option {
+	return func(c *cfg) { c.overrides.Exists = f }
+}
+
+func WithPut(f func(common.PutPrm) (common.PutRes, error)) Option {
+	return func(c *cfg) { c.overrides.Put = f }
+}
+
+func WithDelete(f func(common.DeletePrm) (common.DeleteRes, error)) Option {
+	return func(c *cfg) { c.overrides.Delete = f }
+}
+
+func WithIterate(f func(common.IteratePrm) (common.IterateRes, error)) Option {
+	return func(c *cfg) { c.overrides.Iterate = f }
+}

pkg/local_object_storage/blobstor/teststore/teststore.go

@@ -0,0 +1,215 @@
+// Package teststore provides a common.Storage implementation for testing/mocking purposes.
+//
+// A new teststore.TestStore can be obtained with teststore.New. Whenever one of the common.Storage
+// methods is called, the implementation selects what function to call in the following order:
+//  1. If an override for that method was provided at construction time (via teststore.WithXXX()) or
+//     afterwards via SetOption, that override is used.
+//  2. If a substorage was provided at construction time (via teststore.WithSubstorage()) or afterwars
+//     via SetOption, the corresponding method in the substorage is used.
+//  3. If none of the above apply, the call panics with an error describing the unexpected call.
+//
+// It's safe to call SetOption and the overrides from multiple goroutines, but it's the override's
+// responsibility to ensure safety of whatever operation it executes.
+package teststore
+
+import (
+	"errors"
+	"fmt"
+	"sync"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/compression"
+)
+
+// TestStore is a common.Storage implementation for testing/mocking purposes.
+type TestStore struct {
+	mu sync.RWMutex
+	*cfg
+}
+
+// ErrDiskExploded is a phony error which can be used for testing purposes to differentiate it from
+// more common errors.
+var ErrDiskExploded = errors.New("disk exploded")
+
+// New returns a teststore.TestStore from the given options.
+func New(opts ...Option) *TestStore {
+	c := &cfg{}
+	for _, opt := range opts {
+		opt(c)
+	}
+	return &TestStore{cfg: c}
+}
+
+// SetOption overrides an option of an existing teststore.TestStore.
+// This is useful for overriding methods during a test so that different
+// behaviors are simulated.
+func (s *TestStore) SetOption(opt Option) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	opt(s.cfg)
+}
+
+func (s *TestStore) Open(readOnly bool) error {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	switch {
+	case s.overrides.Open != nil:
+		return s.overrides.Open(readOnly)
+	case s.st != nil:
+		return s.st.Open(readOnly)
+	default:
+		panic(fmt.Sprintf("unexpected storage call: Open(%v)", readOnly))
+	}
+}
+
+func (s *TestStore) Init() error {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	switch {
+	case s.overrides.Init != nil:
+		return s.overrides.Init()
+	case s.st != nil:
+		return s.st.Init()
+	default:
+		panic("unexpected storage call: Init()")
+	}
+}
+
+func (s *TestStore) Close() error {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	switch {
+	case s.overrides.Close != nil:
+		return s.overrides.Close()
+	case s.st != nil:
+		return s.st.Close()
+	default:
+		panic("unexpected storage call: Close()")
+	}
+}
+
+func (s *TestStore) Type() string {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	switch {
+	case s.overrides.Type != nil:
+		return s.overrides.Type()
+	case s.st != nil:
+		return s.st.Type()
+	default:
+		panic("unexpected storage call: Type()")
+	}
+}
+
+func (s *TestStore) Path() string {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	switch {
+	case s.overrides.Path != nil:
+		return s.overrides.Path()
+	case s.st != nil:
+		return s.st.Path()
+	default:
+		panic("unexpected storage call: Path()")
+	}
+}
+
+func (s *TestStore) SetCompressor(cc *compression.Config) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	switch {
+	case s.overrides.SetCompressor != nil:
+		s.overrides.SetCompressor(cc)
+	case s.st != nil:
+		s.st.SetCompressor(cc)
+	default:
+		panic(fmt.Sprintf("unexpected storage call: SetCompressor(%+v)", cc))
+	}
+}
+
+func (s *TestStore) SetReportErrorFunc(f func(string, error)) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	switch {
+	case s.overrides.SetReportErrorFunc != nil:
+		s.overrides.SetReportErrorFunc(f)
+	case s.st != nil:
+		s.st.SetReportErrorFunc(f)
+	default:
+		panic("unexpected storage call: SetReportErrorFunc(<func>)")
+	}
+}
+
+func (s *TestStore) Get(req common.GetPrm) (common.GetRes, error) {
+	switch {
+	case s.overrides.Get != nil:
+		return s.overrides.Get(req)
+	case s.st != nil:
+		return s.st.Get(req)
+	default:
+		panic(fmt.Sprintf("unexpected storage call: Get(%+v)", req))
+	}
+}
+
+func (s *TestStore) GetRange(req common.GetRangePrm) (common.GetRangeRes, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	switch {
+	case s.overrides.GetRange != nil:
+		return s.overrides.GetRange(req)
+	case s.st != nil:
+		return s.st.GetRange(req)
+	default:
+		panic(fmt.Sprintf("unexpected storage call: GetRange(%+v)", req))
+	}
+}
+
+func (s *TestStore) Exists(req common.ExistsPrm) (common.ExistsRes, error) {
+	switch {
+	case s.overrides.Exists != nil:
+		return s.overrides.Exists(req)
+	case s.st != nil:
+		return s.st.Exists(req)
+	default:
+		panic(fmt.Sprintf("unexpected storage call: Exists(%+v)", req))
+	}
+}
+
+func (s *TestStore) Put(req common.PutPrm) (common.PutRes, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	switch {
+	case s.overrides.Put != nil:
+		return s.overrides.Put(req)
+	case s.st != nil:
+		return s.st.Put(req)
+	default:
+		panic(fmt.Sprintf("unexpected storage call: Put(%+v)", req))
+	}
+}
+
+func (s *TestStore) Delete(req common.DeletePrm) (common.DeleteRes, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	switch {
+	case s.overrides.Delete != nil:
+		return s.overrides.Delete(req)
+	case s.st != nil:
+		return s.st.Delete(req)
+	default:
+		panic(fmt.Sprintf("unexpected storage call: Delete(%+v)", req))
+	}
+}
+
+func (s *TestStore) Iterate(req common.IteratePrm) (common.IterateRes, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	switch {
+	case s.overrides.Iterate != nil:
+		return s.overrides.Iterate(req)
+	case s.st != nil:
+		return s.st.Iterate(req)
+	default:
+		panic(fmt.Sprintf("unexpected storage call: Iterate(%+v)", req))
+	}
+}

pkg/local_object_storage/engine/control_test.go

@@ -3,14 +3,17 @@ package engine
 import (
 	"errors"
 	"fmt"
+	"io/fs"
 	"os"
 	"path/filepath"
 	"strconv"
+	"sync/atomic"
 	"testing"
 	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/teststore"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/testutil"
 	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/pilorama"
@@ -25,92 +28,128 @@ import (
 )
 
 // TestInitializationFailure checks that shard is initialized and closed even if media
-// under any single component is absent. We emulate this with permission denied error.
+// under any single component is absent.
 func TestInitializationFailure(t *testing.T) {
-	type paths struct {
-		blobstor   string
-		metabase   string
-		writecache string
-		pilorama   string
+	type openFileFunc func(string, int, fs.FileMode) (*os.File, error)
+
+	type testShardOpts struct {
+		openFileMetabase   openFileFunc
+		openFileWriteCache openFileFunc
+		openFilePilorama   openFileFunc
 	}
 
-	existsDir := filepath.Join(t.TempDir(), "shard")
-	badDir := filepath.Join(t.TempDir(), "missing")
-
-	testShard := func(c paths) []shard.Option {
+	testShard := func(opts testShardOpts) ([]shard.Option, *teststore.TestStore, *teststore.TestStore) {
 		sid, err := generateShardID()
 		require.NoError(t, err)
 
+		tempDir := t.TempDir()
+		blobstorPath := filepath.Join(tempDir, "bs")
+		metabasePath := filepath.Join(tempDir, "mb")
+		writecachePath := filepath.Join(tempDir, "wc")
+		piloramaPath := filepath.Join(tempDir, "pl")
+
+		storages, smallFileStorage, largeFileStorage := newTestStorages(blobstorPath, 1<<20)
+
 		return []shard.Option{
 			shard.WithID(sid),
 			shard.WithLogger(&logger.Logger{Logger: zaptest.NewLogger(t)}),
 			shard.WithBlobStorOptions(
-				blobstor.WithStorages(
-					newStorages(c.blobstor, 1<<20))),
+				blobstor.WithStorages(storages)),
 			shard.WithMetaBaseOptions(
 				meta.WithBoltDBOptions(&bbolt.Options{
-					Timeout: 100 * time.Millisecond,
+					Timeout:  100 * time.Millisecond,
+					OpenFile: opts.openFileMetabase,
 				}),
-				meta.WithPath(c.metabase),
+				meta.WithPath(metabasePath),
 				meta.WithPermissions(0700),
 				meta.WithEpochState(epochState{})),
 			shard.WithWriteCache(true),
-			shard.WithWriteCacheOptions(writecache.WithPath(c.writecache)),
-			shard.WithPiloramaOptions(pilorama.WithPath(c.pilorama)),
-		}
+			shard.WithWriteCacheOptions(
+				writecache.WithPath(writecachePath),
+				writecache.WithOpenFile(opts.openFileWriteCache),
+			),
+			shard.WithPiloramaOptions(
+				pilorama.WithPath(piloramaPath),
+				pilorama.WithOpenFile(opts.openFilePilorama),
+			),
+		}, smallFileStorage, largeFileStorage
 	}
 
 	t.Run("blobstor", func(t *testing.T) {
-		badDir := filepath.Join(badDir, t.Name())
-		require.NoError(t, os.MkdirAll(badDir, os.ModePerm))
-		require.NoError(t, os.Chmod(badDir, 0))
-		testEngineFailInitAndReload(t, badDir, false, testShard(paths{
-			blobstor:   filepath.Join(badDir, "0"),
-			metabase:   filepath.Join(existsDir, t.Name(), "1"),
-			writecache: filepath.Join(existsDir, t.Name(), "2"),
-			pilorama:   filepath.Join(existsDir, t.Name(), "3"),
+		shardOpts, _, largeFileStorage := testShard(testShardOpts{
+			openFileMetabase:   os.OpenFile,
+			openFileWriteCache: os.OpenFile,
+			openFilePilorama:   os.OpenFile,
+		})
+		largeFileStorage.SetOption(teststore.WithOpen(func(ro bool) error {
+			return teststore.ErrDiskExploded
 		}))
+		beforeReload := func() {
+			largeFileStorage.SetOption(teststore.WithOpen(nil))
+		}
+		testEngineFailInitAndReload(t, false, shardOpts, beforeReload)
 	})
 	t.Run("metabase", func(t *testing.T) {
-		badDir := filepath.Join(badDir, t.Name())
-		require.NoError(t, os.MkdirAll(badDir, os.ModePerm))
-		require.NoError(t, os.Chmod(badDir, 0))
-		testEngineFailInitAndReload(t, badDir, true, testShard(paths{
-			blobstor:   filepath.Join(existsDir, t.Name(), "0"),
-			metabase:   filepath.Join(badDir, "1"),
-			writecache: filepath.Join(existsDir, t.Name(), "2"),
-			pilorama:   filepath.Join(existsDir, t.Name(), "3"),
-		}))
+		var openFileMetabaseSucceed atomic.Bool
+		openFileMetabase := func(p string, f int, mode fs.FileMode) (*os.File, error) {
+			if openFileMetabaseSucceed.Load() {
+				return os.OpenFile(p, f, mode)
+			}
+			return nil, teststore.ErrDiskExploded
+		}
+		beforeReload := func() {
+			openFileMetabaseSucceed.Store(true)
+		}
+		shardOpts, _, _ := testShard(testShardOpts{
+			openFileMetabase:   openFileMetabase,
+			openFileWriteCache: os.OpenFile,
+			openFilePilorama:   os.OpenFile,
+		})
+		testEngineFailInitAndReload(t, true, shardOpts, beforeReload)
 	})
 	t.Run("write-cache", func(t *testing.T) {
-		badDir := filepath.Join(badDir, t.Name())
-		require.NoError(t, os.MkdirAll(badDir, os.ModePerm))
-		require.NoError(t, os.Chmod(badDir, 0))
-		testEngineFailInitAndReload(t, badDir, false, testShard(paths{
-			blobstor:   filepath.Join(existsDir, t.Name(), "0"),
-			metabase:   filepath.Join(existsDir, t.Name(), "1"),
-			writecache: filepath.Join(badDir, "2"),
-			pilorama:   filepath.Join(existsDir, t.Name(), "3"),
-		}))
+		var openFileWriteCacheSucceed atomic.Bool
+		openFileWriteCache := func(p string, f int, mode fs.FileMode) (*os.File, error) {
+			if openFileWriteCacheSucceed.Load() {
+				return os.OpenFile(p, f, mode)
+			}
+			return nil, teststore.ErrDiskExploded
+		}
+		beforeReload := func() {
+			openFileWriteCacheSucceed.Store(true)
+		}
+		shardOpts, _, _ := testShard(testShardOpts{
+			openFileMetabase:   os.OpenFile,
+			openFileWriteCache: openFileWriteCache,
+			openFilePilorama:   os.OpenFile,
+		})
+		testEngineFailInitAndReload(t, false, shardOpts, beforeReload)
 	})
 	t.Run("pilorama", func(t *testing.T) {
-		badDir := filepath.Join(badDir, t.Name())
-		require.NoError(t, os.MkdirAll(badDir, os.ModePerm))
-		require.NoError(t, os.Chmod(badDir, 0))
-		testEngineFailInitAndReload(t, badDir, false, testShard(paths{
-			blobstor:   filepath.Join(existsDir, t.Name(), "0"),
-			metabase:   filepath.Join(existsDir, t.Name(), "1"),
-			writecache: filepath.Join(existsDir, t.Name(), "2"),
-			pilorama:   filepath.Join(badDir, "3"),
-		}))
+		var openFilePiloramaSucceed atomic.Bool
+		openFilePilorama := func(p string, f int, mode fs.FileMode) (*os.File, error) {
+			if openFilePiloramaSucceed.Load() {
+				return os.OpenFile(p, f, mode)
+			}
+			return nil, teststore.ErrDiskExploded
+		}
+		beforeReload := func() {
+			openFilePiloramaSucceed.Store(true)
+		}
+		shardOpts, _, _ := testShard(testShardOpts{
+			openFileMetabase:   os.OpenFile,
+			openFileWriteCache: os.OpenFile,
+			openFilePilorama:   openFilePilorama,
+		})
+		testEngineFailInitAndReload(t, false, shardOpts, beforeReload)
 	})
 }
 
-func testEngineFailInitAndReload(t *testing.T, badDir string, errOnAdd bool, s []shard.Option) {
+func testEngineFailInitAndReload(t *testing.T, errOnAdd bool, opts []shard.Option, beforeReload func()) {
 	var configID string
 
 	e := New()
-	_, err := e.AddShard(s...)
+	_, err := e.AddShard(opts...)
 	if errOnAdd {
 		require.Error(t, err)
 		// This branch is only taken when we cannot update shard ID in the metabase.
@@ -139,9 +178,10 @@ func testEngineFailInitAndReload(t *testing.T, badDir string, errOnAdd bool, s [
 	e.mtx.RUnlock()
 	require.Equal(t, 0, shardCount)
 
-	require.NoError(t, os.Chmod(badDir, os.ModePerm))
+	beforeReload()
+
 	require.NoError(t, e.Reload(ReConfiguration{
-		shards: map[string][]shard.Option{configID: s},
+		shards: map[string][]shard.Option{configID: opts},
 	}))
 
 	e.mtx.RLock()
@@ -193,26 +233,28 @@ func TestPersistentShardID(t *testing.T) {
 	dir, err := os.MkdirTemp("", "*")
 	require.NoError(t, err)
 
-	e, _, id := newEngineWithErrorThreshold(t, dir, 1)
+	te := newEngineWithErrorThreshold(t, dir, 1)
 
-	checkShardState(t, e, id[0], 0, mode.ReadWrite)
-	require.NoError(t, e.Close())
+	checkShardState(t, te.ng, te.shards[0].id, 0, mode.ReadWrite)
+	require.NoError(t, te.ng.Close())
 
-	e, _, newID := newEngineWithErrorThreshold(t, dir, 1)
-	require.Equal(t, id, newID)
-	require.NoError(t, e.Close())
+	newTe := newEngineWithErrorThreshold(t, dir, 1)
+	for i := 0; i < len(newTe.shards); i++ {
+		require.Equal(t, te.shards[i].id, newTe.shards[i].id)
+	}
+	require.NoError(t, newTe.ng.Close())
 
-	p1 := e.shards[id[0].String()].Shard.DumpInfo().MetaBaseInfo.Path
-	p2 := e.shards[id[1].String()].Shard.DumpInfo().MetaBaseInfo.Path
+	p1 := newTe.ng.shards[te.shards[0].id.String()].Shard.DumpInfo().MetaBaseInfo.Path
+	p2 := newTe.ng.shards[te.shards[1].id.String()].Shard.DumpInfo().MetaBaseInfo.Path
 	tmp := filepath.Join(dir, "tmp")
 	require.NoError(t, os.Rename(p1, tmp))
 	require.NoError(t, os.Rename(p2, p1))
 	require.NoError(t, os.Rename(tmp, p2))
 
-	e, _, newID = newEngineWithErrorThreshold(t, dir, 1)
-	require.Equal(t, id[1], newID[0])
-	require.Equal(t, id[0], newID[1])
-	require.NoError(t, e.Close())
+	newTe = newEngineWithErrorThreshold(t, dir, 1)
+	require.Equal(t, te.shards[1].id, newTe.shards[0].id)
+	require.Equal(t, te.shards[0].id, newTe.shards[1].id)
+	require.NoError(t, newTe.ng.Close())
 
 }
 

pkg/local_object_storage/engine/engine_test.go

@@ -9,6 +9,7 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/blobovniczatree"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/fstree"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/teststore"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/testutil"
 	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/pilorama"
@@ -115,6 +116,32 @@ func newStorages(root string, smallSize uint64) []blobstor.SubStorage {
 	}
 }
 
+func newTestStorages(root string, smallSize uint64) ([]blobstor.SubStorage, *teststore.TestStore, *teststore.TestStore) {
+	smallFileStorage := teststore.New(
+		teststore.WithSubstorage(blobovniczatree.NewBlobovniczaTree(
+			blobovniczatree.WithRootPath(filepath.Join(root, "blobovnicza")),
+			blobovniczatree.WithBlobovniczaShallowDepth(1),
+			blobovniczatree.WithBlobovniczaShallowWidth(1),
+			blobovniczatree.WithPermissions(0700)),
+		))
+	largeFileStorage := teststore.New(
+		teststore.WithSubstorage(fstree.New(
+			fstree.WithPath(root),
+			fstree.WithDepth(1)),
+		))
+	return []blobstor.SubStorage{
+		{
+			Storage: smallFileStorage,
+			Policy: func(_ *object.Object, data []byte) bool {
+				return uint64(len(data)) < smallSize
+			},
+		},
+		{
+			Storage: largeFileStorage,
+		},
+	}, smallFileStorage, largeFileStorage
+}
+
 func testNewShard(t testing.TB, id int) *shard.Shard {
 	sid, err := generateShardID()
 	require.NoError(t, err)

pkg/local_object_storage/engine/error_test.go

@@ -9,6 +9,8 @@ import (
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/teststore"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/testutil"
 	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/pilorama"
@@ -24,7 +26,19 @@ import (
 
 const errSmallSize = 256
 
-func newEngineWithErrorThreshold(t testing.TB, dir string, errThreshold uint32) (*StorageEngine, string, [2]*shard.ID) {
+type testEngine struct {
+	ng     *StorageEngine
+	dir    string
+	shards [2]*testShard
+}
+
+type testShard struct {
+	id               *shard.ID
+	smallFileStorage *teststore.TestStore
+	largeFileStorage *teststore.TestStore
+}
+
+func newEngineWithErrorThreshold(t testing.TB, dir string, errThreshold uint32) *testEngine {
 	if dir == "" {
 		var err error
 
@@ -38,14 +52,13 @@ func newEngineWithErrorThreshold(t testing.TB, dir string, errThreshold uint32)
 		WithShardPoolSize(1),
 		WithErrorThreshold(errThreshold))
 
-	var ids [2]*shard.ID
-	var err error
+	var testShards [2]*testShard
 
-	for i := range ids {
-		ids[i], err = e.AddShard(
+	for i := range testShards {
+		storages, smallFileStorage, largeFileStorage := newTestStorages(filepath.Join(dir, strconv.Itoa(i)), errSmallSize)
+		id, err := e.AddShard(
 			shard.WithLogger(&logger.Logger{Logger: zaptest.NewLogger(t)}),
-			shard.WithBlobStorOptions(
-				blobstor.WithStorages(newStorages(filepath.Join(dir, strconv.Itoa(i)), errSmallSize))),
+			shard.WithBlobStorOptions(blobstor.WithStorages(storages)),
 			shard.WithMetaBaseOptions(
 				meta.WithPath(filepath.Join(dir, fmt.Sprintf("%d.metabase", i))),
 				meta.WithPermissions(0700),
@@ -55,94 +68,111 @@ func newEngineWithErrorThreshold(t testing.TB, dir string, errThreshold uint32)
 				pilorama.WithPath(filepath.Join(dir, fmt.Sprintf("%d.pilorama", i))),
 				pilorama.WithPerm(0700)))
 		require.NoError(t, err)
+
+		testShards[i] = &testShard{
+			id:               id,
+			smallFileStorage: smallFileStorage,
+			largeFileStorage: largeFileStorage,
+		}
 	}
 	require.NoError(t, e.Open())
 	require.NoError(t, e.Init())
 
-	return e, dir, ids
+	return &testEngine{
+		ng:     e,
+		dir:    dir,
+		shards: testShards,
+	}
 }
 
 func TestErrorReporting(t *testing.T) {
 	t.Run("ignore errors by default", func(t *testing.T) {
-		e, dir, id := newEngineWithErrorThreshold(t, "", 0)
+		te := newEngineWithErrorThreshold(t, "", 0)
 
 		obj := testutil.GenerateObjectWithCID(cidtest.ID())
 		obj.SetPayload(make([]byte, errSmallSize))
 
 		var prm shard.PutPrm
 		prm.SetObject(obj)
-		e.mtx.RLock()
-		_, err := e.shards[id[0].String()].Shard.Put(prm)
-		e.mtx.RUnlock()
+		te.ng.mtx.RLock()
+		_, err := te.ng.shards[te.shards[0].id.String()].Shard.Put(prm)
+		te.ng.mtx.RUnlock()
 		require.NoError(t, err)
 
-		_, err = e.Get(GetPrm{addr: object.AddressOf(obj)})
+		_, err = te.ng.Get(GetPrm{addr: object.AddressOf(obj)})
 		require.NoError(t, err)
 
-		checkShardState(t, e, id[0], 0, mode.ReadWrite)
-		checkShardState(t, e, id[1], 0, mode.ReadWrite)
+		checkShardState(t, te.ng, te.shards[0].id, 0, mode.ReadWrite)
+		checkShardState(t, te.ng, te.shards[1].id, 0, mode.ReadWrite)
 
-		corruptSubDir(t, filepath.Join(dir, "0"))
+		for _, shard := range te.shards {
+			shard.largeFileStorage.SetOption(teststore.WithGet(func(common.GetPrm) (common.GetRes, error) {
+				return common.GetRes{}, teststore.ErrDiskExploded
+			}))
+		}
 
 		for i := uint32(1); i < 3; i++ {
-			_, err = e.Get(GetPrm{addr: object.AddressOf(obj)})
+			_, err = te.ng.Get(GetPrm{addr: object.AddressOf(obj)})
 			require.Error(t, err)
-			checkShardState(t, e, id[0], i, mode.ReadWrite)
-			checkShardState(t, e, id[1], 0, mode.ReadWrite)
+			checkShardState(t, te.ng, te.shards[0].id, i, mode.ReadWrite)
+			checkShardState(t, te.ng, te.shards[1].id, 0, mode.ReadWrite)
 		}
 	})
 	t.Run("with error threshold", func(t *testing.T) {
 		const errThreshold = 3
 
-		e, dir, id := newEngineWithErrorThreshold(t, "", errThreshold)
+		te := newEngineWithErrorThreshold(t, "", errThreshold)
 
 		obj := testutil.GenerateObjectWithCID(cidtest.ID())
 		obj.SetPayload(make([]byte, errSmallSize))
 
 		var prm shard.PutPrm
 		prm.SetObject(obj)
-		e.mtx.RLock()
-		_, err := e.shards[id[0].String()].Put(prm)
-		e.mtx.RUnlock()
+		te.ng.mtx.RLock()
+		_, err := te.ng.shards[te.shards[0].id.String()].Put(prm)
+		te.ng.mtx.RUnlock()
 		require.NoError(t, err)
 
-		_, err = e.Get(GetPrm{addr: object.AddressOf(obj)})
+		_, err = te.ng.Get(GetPrm{addr: object.AddressOf(obj)})
 		require.NoError(t, err)
 
-		checkShardState(t, e, id[0], 0, mode.ReadWrite)
-		checkShardState(t, e, id[1], 0, mode.ReadWrite)
+		checkShardState(t, te.ng, te.shards[0].id, 0, mode.ReadWrite)
+		checkShardState(t, te.ng, te.shards[1].id, 0, mode.ReadWrite)
 
-		corruptSubDir(t, filepath.Join(dir, "0"))
+		for _, shard := range te.shards {
+			shard.largeFileStorage.SetOption(teststore.WithGet(func(common.GetPrm) (common.GetRes, error) {
+				return common.GetRes{}, teststore.ErrDiskExploded
+			}))
+		}
 
 		for i := uint32(1); i < errThreshold; i++ {
-			_, err = e.Get(GetPrm{addr: object.AddressOf(obj)})
+			_, err = te.ng.Get(GetPrm{addr: object.AddressOf(obj)})
 			require.Error(t, err)
-			checkShardState(t, e, id[0], i, mode.ReadWrite)
-			checkShardState(t, e, id[1], 0, mode.ReadWrite)
+			checkShardState(t, te.ng, te.shards[0].id, i, mode.ReadWrite)
+			checkShardState(t, te.ng, te.shards[1].id, 0, mode.ReadWrite)
 		}
 
 		for i := uint32(0); i < 2; i++ {
-			_, err = e.Get(GetPrm{addr: object.AddressOf(obj)})
+			_, err = te.ng.Get(GetPrm{addr: object.AddressOf(obj)})
 			require.Error(t, err)
-			checkShardState(t, e, id[0], errThreshold+i, mode.DegradedReadOnly)
-			checkShardState(t, e, id[1], 0, mode.ReadWrite)
+			checkShardState(t, te.ng, te.shards[0].id, errThreshold+i, mode.DegradedReadOnly)
+			checkShardState(t, te.ng, te.shards[1].id, 0, mode.ReadWrite)
 		}
 
-		require.NoError(t, e.SetShardMode(id[0], mode.ReadWrite, false))
-		checkShardState(t, e, id[0], errThreshold+1, mode.ReadWrite)
+		require.NoError(t, te.ng.SetShardMode(te.shards[0].id, mode.ReadWrite, false))
+		checkShardState(t, te.ng, te.shards[0].id, errThreshold+1, mode.ReadWrite)
 
-		require.NoError(t, e.SetShardMode(id[0], mode.ReadWrite, true))
-		checkShardState(t, e, id[0], 0, mode.ReadWrite)
+		require.NoError(t, te.ng.SetShardMode(te.shards[0].id, mode.ReadWrite, true))
+		checkShardState(t, te.ng, te.shards[0].id, 0, mode.ReadWrite)
 	})
 }
 
-// Issue #1186.
 func TestBlobstorFailback(t *testing.T) {
 	dir, err := os.MkdirTemp("", "*")
 	require.NoError(t, err)
 	t.Cleanup(func() { require.NoError(t, os.RemoveAll(dir)) })
 
-	e, _, id := newEngineWithErrorThreshold(t, dir, 1)
+	te := newEngineWithErrorThreshold(t, dir, 1)
 
 	objs := make([]*objectSDK.Object, 0, 2)
 	for _, size := range []int{15, errSmallSize + 1} {
@@ -151,49 +181,49 @@ func TestBlobstorFailback(t *testing.T) {
 
 		var prm shard.PutPrm
 		prm.SetObject(obj)
-		e.mtx.RLock()
-		_, err = e.shards[id[0].String()].Shard.Put(prm)
-		e.mtx.RUnlock()
+		te.ng.mtx.RLock()
+		_, err = te.ng.shards[te.shards[0].id.String()].Shard.Put(prm)
+		te.ng.mtx.RUnlock()
 		require.NoError(t, err)
 		objs = append(objs, obj)
 	}
 
 	for i := range objs {
 		addr := object.AddressOf(objs[i])
-		_, err = e.Get(GetPrm{addr: addr})
+		_, err = te.ng.Get(GetPrm{addr: addr})
 		require.NoError(t, err)
-		_, err = e.GetRange(RngPrm{addr: addr})
+		_, err = te.ng.GetRange(RngPrm{addr: addr})
 		require.NoError(t, err)
 	}
 
-	checkShardState(t, e, id[0], 0, mode.ReadWrite)
-	require.NoError(t, e.Close())
+	checkShardState(t, te.ng, te.shards[0].id, 0, mode.ReadWrite)
+	require.NoError(t, te.ng.Close())
 
-	p1 := e.shards[id[0].String()].Shard.DumpInfo().BlobStorInfo.SubStorages[1].Path
-	p2 := e.shards[id[1].String()].Shard.DumpInfo().BlobStorInfo.SubStorages[1].Path
+	p1 := te.ng.shards[te.shards[0].id.String()].Shard.DumpInfo().BlobStorInfo.SubStorages[1].Path
+	p2 := te.ng.shards[te.shards[1].id.String()].Shard.DumpInfo().BlobStorInfo.SubStorages[1].Path
 	tmp := filepath.Join(dir, "tmp")
 	require.NoError(t, os.Rename(p1, tmp))
 	require.NoError(t, os.Rename(p2, p1))
 	require.NoError(t, os.Rename(tmp, p2))
 
-	e, _, id = newEngineWithErrorThreshold(t, dir, 1)
+	te = newEngineWithErrorThreshold(t, dir, 1)
 
 	for i := range objs {
 		addr := object.AddressOf(objs[i])
-		getRes, err := e.Get(GetPrm{addr: addr})
+		getRes, err := te.ng.Get(GetPrm{addr: addr})
 		require.NoError(t, err)
 		require.Equal(t, objs[i], getRes.Object())
 
-		rngRes, err := e.GetRange(RngPrm{addr: addr, off: 1, ln: 10})
+		rngRes, err := te.ng.GetRange(RngPrm{addr: addr, off: 1, ln: 10})
 		require.NoError(t, err)
 		require.Equal(t, objs[i].Payload()[1:11], rngRes.Object().Payload())
 
-		_, err = e.GetRange(RngPrm{addr: addr, off: errSmallSize + 10, ln: 1})
+		_, err = te.ng.GetRange(RngPrm{addr: addr, off: errSmallSize + 10, ln: 1})
 		require.ErrorAs(t, err, &apistatus.ObjectOutOfRange{})
 	}
 
-	checkShardState(t, e, id[0], 1, mode.DegradedReadOnly)
-	checkShardState(t, e, id[1], 0, mode.ReadWrite)
+	checkShardState(t, te.ng, te.shards[0].id, 1, mode.DegradedReadOnly)
+	checkShardState(t, te.ng, te.shards[1].id, 0, mode.ReadWrite)
 }
 
 func checkShardState(t *testing.T, e *StorageEngine, id *shard.ID, errCount uint32, mode mode.Mode) {
@@ -204,19 +234,3 @@ func checkShardState(t *testing.T, e *StorageEngine, id *shard.ID, errCount uint
 	require.Equal(t, errCount, sh.errorCount.Load())
 	require.Equal(t, mode, sh.GetMode())
 }
-
-// corruptSubDir makes random directory except "blobovnicza" in blobstor FSTree unreadable.
-func corruptSubDir(t *testing.T, dir string) {
-	de, err := os.ReadDir(dir)
-	require.NoError(t, err)
-
-	// FIXME(@cthulhu-rider): copy-paste of unexported const from blobstor package, see #1407
-	const dirBlobovnicza = "blobovnicza"
-
-	for i := range de {
-		if de[i].IsDir() && de[i].Name() != dirBlobovnicza {
-			require.NoError(t, os.Chmod(filepath.Join(dir, de[i].Name()), 0))
-			return
-		}
-	}
-}

pkg/local_object_storage/engine/lock_test.go

@@ -17,7 +17,6 @@ import (
 	cidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id/test"
 	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
 	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
-	objecttest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id/test"
 	oidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id/test"
 	"github.com/panjf2000/ants/v2"
 	"github.com/stretchr/testify/require"
@@ -191,7 +190,7 @@ func TestLockExpiration(t *testing.T) {
 	require.NoError(t, err)
 
 	var inhumePrm InhumePrm
-	inhumePrm.WithTarget(objecttest.Address(), objectcore.AddressOf(obj))
+	inhumePrm.WithTarget(oidtest.Address(), objectcore.AddressOf(obj))
 
 	_, err = e.Inhume(inhumePrm)
 	require.ErrorAs(t, err, new(apistatus.ObjectLocked))
@@ -204,7 +203,7 @@ func TestLockExpiration(t *testing.T) {
 	time.Sleep(time.Second)
 
 	// 4.
-	inhumePrm.WithTarget(objecttest.Address(), objectcore.AddressOf(obj))
+	inhumePrm.WithTarget(oidtest.Address(), objectcore.AddressOf(obj))
 
 	_, err = e.Inhume(inhumePrm)
 	require.NoError(t, err)
@@ -263,7 +262,7 @@ func TestLockForceRemoval(t *testing.T) {
 	_, err = e.Inhume(inhumePrm)
 	require.ErrorAs(t, err, new(apistatus.ObjectLocked))
 
-	inhumePrm.WithTarget(objecttest.Address(), objectcore.AddressOf(obj))
+	inhumePrm.WithTarget(oidtest.Address(), objectcore.AddressOf(obj))
 
 	_, err = e.Inhume(inhumePrm)
 	require.ErrorAs(t, err, new(apistatus.ObjectLocked))

pkg/local_object_storage/engine/tree_test.go

@@ -23,7 +23,7 @@ func BenchmarkTreeVsSearch(b *testing.B) {
 }
 
 func benchmarkTreeVsSearch(b *testing.B, objCount int) {
-	e, _, _ := newEngineWithErrorThreshold(b, "", 0)
+	te := newEngineWithErrorThreshold(b, "", 0)
 	cid := cidtest.ID()
 	d := pilorama.CIDDescriptor{CID: cid, Position: 0, Size: 1}
 	treeID := "someTree"
@@ -31,11 +31,11 @@ func benchmarkTreeVsSearch(b *testing.B, objCount int) {
 	for i := 0; i < objCount; i++ {
 		obj := testutil.GenerateObjectWithCID(cid)
 		testutil.AddAttribute(obj, pilorama.AttributeFilename, strconv.Itoa(i))
-		err := Put(e, obj)
+		err := Put(te.ng, obj)
 		if err != nil {
 			b.Fatal(err)
 		}
-		_, err = e.TreeAddByPath(d, treeID, pilorama.AttributeFilename, nil,
+		_, err = te.ng.TreeAddByPath(d, treeID, pilorama.AttributeFilename, nil,
 			[]pilorama.KeyValue{{pilorama.AttributeFilename, []byte(strconv.Itoa(i))}})
 		if err != nil {
 			b.Fatal(err)
@@ -51,7 +51,7 @@ func benchmarkTreeVsSearch(b *testing.B, objCount int) {
 		prm.WithFilters(fs)
 
 		for i := 0; i < b.N; i++ {
-			res, err := e.Select(prm)
+			res, err := te.ng.Select(prm)
 			if err != nil {
 				b.Fatal(err)
 			}
@@ -62,7 +62,7 @@ func benchmarkTreeVsSearch(b *testing.B, objCount int) {
 	})
 	b.Run("TreeGetByPath", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
-			nodes, err := e.TreeGetByPath(cid, treeID, pilorama.AttributeFilename, []string{strconv.Itoa(objCount / 2)}, true)
+			nodes, err := te.ng.TreeGetByPath(cid, treeID, pilorama.AttributeFilename, []string{strconv.Itoa(objCount / 2)}, true)
 			if err != nil {
 				b.Fatal(err)
 			}

pkg/local_object_storage/pilorama/boltdb.go

@@ -66,6 +66,7 @@ func NewBoltForest(opts ...Option) ForestStorage {
 			perm:          os.ModePerm,
 			maxBatchDelay: bbolt.DefaultMaxBatchDelay,
 			maxBatchSize:  bbolt.DefaultMaxBatchSize,
+			openFile:      os.OpenFile,
 		},
 	}
 
@@ -107,6 +108,7 @@ func (t *boltForest) Open(readOnly bool) error {
 	opts.ReadOnly = readOnly
 	opts.NoSync = t.noSync
 	opts.Timeout = 100 * time.Millisecond
+	opts.OpenFile = t.openFile
 
 	t.db, err = bbolt.Open(t.path, t.perm, &opts)
 	if err != nil {

pkg/local_object_storage/pilorama/option.go

@@ -2,6 +2,7 @@ package pilorama
 
 import (
 	"io/fs"
+	"os"
 	"time"
 )
 
@@ -13,6 +14,7 @@ type cfg struct {
 	noSync        bool
 	maxBatchDelay time.Duration
 	maxBatchSize  int
+	openFile      func(string, int, fs.FileMode) (*os.File, error)
 }
 
 func WithPath(path string) Option {
@@ -44,3 +46,9 @@ func WithMaxBatchSize(size int) Option {
 		c.maxBatchSize = size
 	}
 }
+
+func WithOpenFile(openFile func(string, int, fs.FileMode) (*os.File, error)) Option {
+	return func(c *cfg) {
+		c.openFile = openFile
+	}
+}

pkg/local_object_storage/shard/control_test.go

@@ -1,14 +1,18 @@
 package shard
 
 import (
+	"io/fs"
+	"math"
 	"os"
 	"path/filepath"
+	"sync/atomic"
 	"testing"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/fstree"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/teststore"
 	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/pilorama"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
@@ -22,6 +26,7 @@ import (
 	oidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id/test"
 	objecttest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/test"
 	"github.com/stretchr/testify/require"
+	"go.etcd.io/bbolt"
 	"go.uber.org/zap/zaptest"
 )
 
@@ -40,19 +45,33 @@ func TestShardOpen(t *testing.T) {
 	dir := t.TempDir()
 	metaPath := filepath.Join(dir, "meta")
 
+	st := teststore.New(teststore.WithSubstorage(fstree.New(
+		fstree.WithDirNameLen(2),
+		fstree.WithPath(filepath.Join(dir, "blob")),
+		fstree.WithDepth(1)),
+	))
+
+	var allowedMode atomic.Int64
+	openFileMetabase := func(p string, f int, perm fs.FileMode) (*os.File, error) {
+		const modeMask = os.O_RDONLY | os.O_RDWR | os.O_WRONLY
+		if int64(f&modeMask) == allowedMode.Load() {
+			return os.OpenFile(p, f, perm)
+		}
+		return nil, fs.ErrPermission
+	}
+
 	newShard := func() *Shard {
 		return New(
 			WithLogger(&logger.Logger{Logger: zaptest.NewLogger(t)}),
 			WithBlobStorOptions(
 				blobstor.WithStorages([]blobstor.SubStorage{
-					{
-						Storage: fstree.New(
-							fstree.WithDirNameLen(2),
-							fstree.WithPath(filepath.Join(dir, "blob")),
-							fstree.WithDepth(1)),
-					},
+					{Storage: st},
 				})),
-			WithMetaBaseOptions(meta.WithPath(metaPath), meta.WithEpochState(epochState{})),
+			WithMetaBaseOptions(
+				meta.WithPath(metaPath),
+				meta.WithEpochState(epochState{}),
+				meta.WithBoltDBOptions(&bbolt.Options{OpenFile: openFileMetabase}),
+			),
 			WithPiloramaOptions(
 				pilorama.WithPath(filepath.Join(dir, "pilorama"))),
 			WithWriteCache(true),
@@ -60,6 +79,8 @@ func TestShardOpen(t *testing.T) {
 				writecache.WithPath(filepath.Join(dir, "wc"))))
 	}
 
+	allowedMode.Store(int64(os.O_RDWR))
+
 	sh := newShard()
 	require.NoError(t, sh.Open())
 	require.NoError(t, sh.Init())
@@ -67,7 +88,8 @@ func TestShardOpen(t *testing.T) {
 	require.NoError(t, sh.Close())
 
 	// Metabase can be opened in read-only => start in ReadOnly mode.
-	require.NoError(t, os.Chmod(metaPath, 0444))
+	allowedMode.Store(int64(os.O_RDONLY))
+
 	sh = newShard()
 	require.NoError(t, sh.Open())
 	require.NoError(t, sh.Init())
@@ -77,7 +99,8 @@ func TestShardOpen(t *testing.T) {
 	require.NoError(t, sh.Close())
 
 	// Metabase is corrupted => start in DegradedReadOnly mode.
-	require.NoError(t, os.Chmod(metaPath, 0000))
+	allowedMode.Store(math.MaxInt64)
+
 	sh = newShard()
 	require.NoError(t, sh.Open())
 	require.NoError(t, sh.Init())

pkg/local_object_storage/writecache/flush_test.go

@@ -46,12 +46,13 @@ func TestFlush(t *testing.T) {
 		require.NoError(t, mb.Open(false))
 		require.NoError(t, mb.Init())
 
-		fsTree := fstree.New(
-			fstree.WithPath(filepath.Join(dir, "blob")),
-			fstree.WithDepth(0),
-			fstree.WithDirNameLen(1))
 		bs := blobstor.New(blobstor.WithStorages([]blobstor.SubStorage{
-			{Storage: fsTree},
+			{
+				Storage: fstree.New(
+					fstree.WithPath(filepath.Join(dir, "blob")),
+					fstree.WithDepth(0),
+					fstree.WithDirNameLen(1)),
+			},
 		}))
 		require.NoError(t, bs.Open(false))
 		require.NoError(t, bs.Init())
@@ -208,7 +209,7 @@ func TestFlush(t *testing.T) {
 
 				_, err = os.Stat(p) // sanity check
 				require.NoError(t, err)
-				require.NoError(t, os.Chmod(p, 0))
+				require.NoError(t, os.Truncate(p, 0)) // corrupt the file contents, so that it can't be unmarshalled
 			})
 		})
 		t.Run("fs, invalid object", func(t *testing.T) {

pkg/local_object_storage/writecache/options.go

@@ -1,6 +1,8 @@
 package writecache
 
 import (
+	"io/fs"
+	"os"
 	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor"
@@ -55,6 +57,8 @@ type options struct {
 	noSync bool
 	// reportError is the function called when encountering disk errors in background workers.
 	reportError func(string, error)
+	// openFile is the function called internally by bbolt to open database files. Useful for hermetic testing.
+	openFile func(string, int, fs.FileMode) (*os.File, error)
 }
 
 // WithLogger sets logger.
@@ -152,3 +156,10 @@ func WithReportErrorFunc(f func(string, error)) Option {
 		o.reportError = f
 	}
 }
+
+// WithOpenFile sets the OpenFile function to use internally by bolt. Useful for hermetic testing.
+func WithOpenFile(f func(string, int, fs.FileMode) (*os.File, error)) Option {
+	return func(o *options) {
+		o.openFile = f
+	}
+}

pkg/local_object_storage/writecache/storage.go

@@ -43,7 +43,7 @@ func (c *cache) openStore(readOnly bool) error {
 		return err
 	}
 
-	c.db, err = OpenDB(c.path, readOnly)
+	c.db, err = OpenDB(c.path, readOnly, c.openFile)
 	if err != nil {
 		return fmt.Errorf("could not open database: %w", err)
 	}

pkg/local_object_storage/writecache/util.go

@@ -1,6 +1,7 @@
 package writecache
 
 import (
+	"io/fs"
 	"os"
 	"path/filepath"
 	"time"
@@ -9,10 +10,11 @@ import (
 )
 
 // OpenDB opens BoltDB instance for write-cache. Opens in read-only mode if ro is true.
-func OpenDB(p string, ro bool) (*bbolt.DB, error) {
+func OpenDB(p string, ro bool, openFile func(string, int, fs.FileMode) (*os.File, error)) (*bbolt.DB, error) {
 	return bbolt.Open(filepath.Join(p, dbName), os.ModePerm, &bbolt.Options{
 		NoFreelistSync: true,
 		ReadOnly:       ro,
 		Timeout:        100 * time.Millisecond,
+		OpenFile:       openFile,
 	})
 }

pkg/local_object_storage/writecache/writecache.go

@@ -1,6 +1,7 @@
 package writecache
 
 import (
+	"os"
 	"sync"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
@@ -106,6 +107,7 @@ func New(opts ...Option) Cache {
 			maxCacheSize:    defaultMaxCacheSize,
 			maxBatchSize:    bbolt.DefaultMaxBatchSize,
 			maxBatchDelay:   bbolt.DefaultMaxBatchDelay,
+			openFile:        os.OpenFile,
 		},
 	}