diff --git a/file/file.go b/file/file.go
index 023ef10..8edd09d 100644
--- a/file/file.go
+++ b/file/file.go
@@ -5,11 +5,11 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
-	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
+	"sync"
 	"time"
 
 	"github.com/faabiosr/cachego"
@@ -18,6 +18,7 @@ import (
 type (
 	file struct {
 		dir string
+		sync.RWMutex
 	}
 
 	fileContent struct {
@@ -30,7 +31,8 @@ const perm = 0o666
 
 // New creates an instance of File cache
 func New(dir string) cachego.Cache {
-	return &file{dir}
+	_ = os.MkdirAll(dir, os.ModePerm)
+	return &file{dir: dir}
 }
 
 func (f *file) createName(key string) string {
@@ -42,6 +44,9 @@ func (f *file) createName(key string) string {
 }
 
 func (f *file) read(key string) (*fileContent, error) {
+	f.RLock()
+	defer f.RUnlock()
+
 	value, err := ioutil.ReadFile(f.createName(key))
 	if err != nil {
 		return nil, err
@@ -56,22 +61,28 @@ func (f *file) read(key string) (*fileContent, error) {
 		return content, nil
 	}
 
-	if content.Duration <= time.Now().Unix() {
-		_ = f.Delete(key)
-		return nil, errors.New("cache expired")
-	}
-
 	return content, nil
 }
 
 // Contains checks if the cached key exists into the File storage
 func (f *file) Contains(key string) bool {
-	_, err := f.read(key)
-	return err == nil
+	content, err := f.read(key)
+	if err != nil {
+		return false
+	}
+
+	if f.isExpired(content) {
+		_ = f.Delete(key)
+		return false
+	}
+	return true
 }
 
 // Delete the cached key from File storage
 func (f *file) Delete(key string) error {
+	f.Lock()
+	defer f.Unlock()
+
 	_, err := os.Stat(f.createName(key))
 	if err != nil && os.IsNotExist(err) {
 		return nil
@@ -87,9 +98,18 @@ func (f *file) Fetch(key string) (string, error) {
 		return "", err
 	}
 
+	if f.isExpired(content) {
+		_ = f.Delete(key)
+		return "", cachego.ErrCacheExpired
+	}
+
 	return content.Data, nil
 }
 
+func (f *file) isExpired(content *fileContent) bool {
+	return content.Duration > 0 && content.Duration <= time.Now().Unix()
+}
+
 // FetchMulti retrieve multiple cached values from keys of the File storage
 func (f *file) FetchMulti(keys []string) map[string]string {
 	result := make(map[string]string)
@@ -105,6 +125,9 @@ func (f *file) FetchMulti(keys []string) map[string]string {
 
 // Flush removes all cached keys of the File storage
 func (f *file) Flush() error {
+	f.Lock()
+	defer f.Unlock()
+
 	dir, err := os.Open(f.dir)
 	if err != nil {
 		return err
@@ -125,14 +148,15 @@ func (f *file) Flush() error {
 
 // Save a value in File storage by key
 func (f *file) Save(key string, value string, lifeTime time.Duration) error {
-	duration := int64(0)
+	f.Lock()
+	defer f.Unlock()
 
+	duration := int64(0)
 	if lifeTime > 0 {
 		duration = time.Now().Unix() + int64(lifeTime.Seconds())
 	}
 
 	content := &fileContent{duration, value}
-
 	data, err := json.Marshal(content)
 	if err != nil {
 		return err
diff --git a/file/file_test.go b/file/file_test.go
index 1ada012..2b55d8c 100644
--- a/file/file_test.go
+++ b/file/file_test.go
@@ -4,6 +4,9 @@ import (
 	"io/ioutil"
 	"testing"
 	"time"
+
+	"github.com/faabiosr/cachego"
+	"github.com/stretchr/testify/assert"
 )
 
 const (
@@ -19,51 +22,41 @@ func TestFile(t *testing.T) {
 
 	c := New(dir)
 
-	if err := c.Save(testKey, testValue, 1*time.Nanosecond); err != nil {
-		t.Errorf("save fail: expected nil, got %v", err)
-	}
+	err = c.Save(testKey, testValue, 1*time.Nanosecond)
+	assert.Equal(t, nil, err)
 
-	if _, err := c.Fetch(testKey); err == nil {
-		t.Errorf("fetch fail: expected an error, got %v", err)
-	}
+	res, err := c.Fetch(testKey)
+	assert.Equal(t, "", res)
+	assert.Equal(t, cachego.ErrCacheExpired, err)
 
-	_ = c.Save(testKey, testValue, 10*time.Second)
+	err = c.Save(testKey, testValue, 10*time.Second)
+	assert.Equal(t, nil, err)
 
-	if res, _ := c.Fetch(testKey); res != testValue {
-		t.Errorf("fetch fail, wrong value: expected %s, got %s", testValue, res)
-	}
+	res, err = c.Fetch(testKey)
+	assert.Equal(t, nil, err)
+	assert.Equal(t, testValue, res)
 
 	_ = c.Save(testKey, testValue, 0)
-
-	if !c.Contains(testKey) {
-		t.Errorf("contains failed: the key %s should be exist", testKey)
-	}
+	assert.Equal(t, true, c.Contains(testKey))
 
 	_ = c.Save("bar", testValue, 0)
 
-	if values := c.FetchMulti([]string{testKey, "bar"}); len(values) == 0 {
-		t.Errorf("fetch multi failed: expected %d, got %d", 2, len(values))
-	}
+	values := c.FetchMulti([]string{testKey, "bar"})
+	assert.Equal(t, 2, len(values))
 
-	if err := c.Flush(); err != nil {
-		t.Errorf("flush failed: expected nil, got %v", err)
-	}
+	err = c.Flush()
+	assert.Equal(t, nil, err)
 
-	if c.Contains(testKey) {
-		t.Errorf("contains failed: the key %s should not be exist", testKey)
-	}
+	assert.Equal(t, false, c.Contains(testKey))
 
 	c = New("./test/")
+	err = c.Save(testKey, testValue, 0)
+	assert.Equal(t, nil, err)
 
-	if err := c.Save(testKey, testValue, 0); err == nil {
-		t.Errorf("save failed: expected an error, got %v", err)
-	}
-
-	if _, err := c.Fetch(testKey); err == nil {
-		t.Errorf("fetch failed: expected and error, got %v", err)
-	}
+	res, err = c.Fetch(testKey)
+	assert.Equal(t, testValue, res)
+	assert.Equal(t, nil, err)
 
-	if err := c.Flush(); err == nil {
-		t.Errorf("flush failed: expected an error, got %v", err)
-	}
+	err = c.Flush()
+	assert.Equal(t, nil, err)
 }
diff --git a/go.mod b/go.mod
index de95f0e..6f099a3 100644
--- a/go.mod
+++ b/go.mod
@@ -6,18 +6,21 @@ require (
 	github.com/bradfitz/gomemcache v0.0.0-20230124162541-5f7a7d875746
 	github.com/mattn/go-sqlite3 v1.14.16
 	github.com/redis/go-redis/v9 v9.0.2
+	github.com/stretchr/testify v1.8.1
 	go.etcd.io/bbolt v1.3.7
 	go.mongodb.org/mongo-driver v1.11.3
 )
 
 require (
 	github.com/cespare/xxhash/v2 v2.2.0 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
 	github.com/golang/snappy v0.0.1 // indirect
 	github.com/google/go-cmp v0.5.5 // indirect
 	github.com/klauspost/compress v1.13.6 // indirect
 	github.com/montanaflynn/stats v0.0.0-20171201202039-1bf9dbcd8cbe // indirect
 	github.com/pkg/errors v0.9.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/xdg-go/pbkdf2 v1.0.0 // indirect
 	github.com/xdg-go/scram v1.1.1 // indirect
 	github.com/xdg-go/stringprep v1.0.3 // indirect
@@ -27,4 +30,5 @@ require (
 	golang.org/x/sys v0.4.0 // indirect
 	golang.org/x/text v0.3.7 // indirect
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
diff --git a/go.sum b/go.sum
index afe1d94..7be6964 100644
--- a/go.sum
+++ b/go.sum
@@ -32,8 +32,13 @@ github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZN
 github.com/redis/go-redis/v9 v9.0.2 h1:BA426Zqe/7r56kCcvxYLWe1mkaz71LKF77GwgFzSxfE=
 github.com/redis/go-redis/v9 v9.0.2/go.mod h1:/xDTe9EF1LM61hek62Poq2nzQSGj0xSrEtEHbBQevps=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
+github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
+github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/tidwall/pretty v1.0.0 h1:HsD+QiTn7sK6flMKIvNmpqz1qrpP3Ps6jOKIKMooyg4=
 github.com/tidwall/pretty v1.0.0/go.mod h1:XNkn88O1ChpSDQmQeStsy+sBenx6DDtFZJxhVysOjyk=
 github.com/xdg-go/pbkdf2 v1.0.0 h1:Su7DPu48wXMwC3bs7MCNG+z4FhcyEuz5dlvchbq0B0c=
@@ -67,6 +72,7 @@ golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8T
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=