Set timestamp of download files (#87)

* Set file timestamp according to S3 timestamp on download

* Check file timestamp on the test

* Tweak format

s3sync.go

@@ -220,7 +220,6 @@ func (m *Manager) download(file *fileInfo, sourcePath *s3Path, destPath string)
 	}
 
 	writer, err := os.Create(targetFilename)
-
 	if err != nil {
 		return err
 	}
@@ -238,7 +237,11 @@ func (m *Manager) download(file *fileInfo, sourcePath *s3Path, destPath string)
 		Bucket: aws.String(sourcePath.bucket),
 		Key:    aws.String(sourceFile),
 	})
+	if err != nil {
+		return err
+	}
 
+	err = os.Chtimes(targetFilename, file.lastModified, file.lastModified)
 	if err != nil {
 		return err
 	}

s3sync_test.go

@@ -22,6 +22,7 @@ import (
 	"sort"
 	"sync/atomic"
 	"testing"
+	"time"
 )
 
 const dummyFilename = "README.md"
@@ -60,6 +61,8 @@ func TestS3sync(t *testing.T) {
 			t.Fatal("Failed to write", err)
 		}
 
+		tBeforeSync := time.Now()
+
 		// The dummy s3 bucket has following files.
 		//
 		// s3://example-bucket/
@@ -74,9 +77,16 @@ func TestS3sync(t *testing.T) {
 		}
 
 		fileHasSize(t, destOnlyFilename, destOnlyFileSize)
-		fileHasSize(t, filepath.Join(temp, dummyFilename), dummyFileSize)
-		fileHasSize(t, filepath.Join(temp, "foo", dummyFilename), dummyFileSize)
-		fileHasSize(t, filepath.Join(temp, "bar/baz", dummyFilename), dummyFileSize)
+
+		for _, filename := range []string{
+			filepath.Join(temp, dummyFilename),
+			filepath.Join(temp, "foo", dummyFilename),
+			filepath.Join(temp, "bar/baz", dummyFilename),
+		} {
+			fileHasSize(t, filename, dummyFileSize)
+			// Files must be made before test
+			fileModTimeBefore(t, filename, tBeforeSync)
+		}
 	})
 	t.Run("DownloadSkipDirectory", func(t *testing.T) {
 		temp, err := ioutil.TempDir("", "s3synctest")
@@ -654,14 +664,3 @@ func (d *dummyLogger) Logf(format string, v ...interface{}) {
 func createLoggerWithLogFunc(log func(v ...interface{})) LoggerIF {
 	return &dummyLogger{log: log}
 }
-
-func fileHasSize(t *testing.T, filename string, expectedSize int) {
-	data, err := ioutil.ReadFile(filename)
-	if err != nil {
-		t.Error(filename, "is not synced")
-		return
-	}
-	if len(data) != expectedSize {
-		t.Error(filename, "is not synced")
-	}
-}

util_test.go

@@ -13,8 +13,11 @@
 package s3sync
 
 import (
+	"io/ioutil"
+	"os"
 	"sort"
 	"testing"
+	"time"
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/session"
@@ -96,3 +99,25 @@ func listObjectsSorted(t *testing.T, bucket string) []s3Object {
 	sort.Sort(s3ObjectList(objs))
 	return objs
 }
+
+func fileHasSize(t *testing.T, filename string, expectedSize int) {
+	data, err := ioutil.ReadFile(filename)
+	if err != nil {
+		t.Error(filename, "is not synced")
+		return
+	}
+	if n := len(data); n != expectedSize {
+		t.Errorf("%s is not synced (file size is expected to be %d, actual %d)", filename, expectedSize, n)
+	}
+}
+
+func fileModTimeBefore(t *testing.T, filename string, t0 time.Time) {
+	info, err := os.Stat(filename)
+	if err != nil {
+		t.Error("Failed to get stat:", err)
+		return
+	}
+	if t1 := info.ModTime(); !t1.Before(t0) {
+		t.Errorf("File modification time %v is later than %v", t1, t0)
+	}
+}