@@ -183,3 +183,10 @@ func TestMoveToSubdir(t *testing.T) {

 		t.Fatalf("Results after migration do not equal list of files: expected: %v, got: %v", filesList, results)

 	}

 }

+

+// Test a non-existing directory

+func TestSizeNonExistingDirectory(t *testing.T) {

+	if _, err := Size("/thisdirectoryshouldnotexist/TestSizeNonExistingDirectory"); err == nil {

+		t.Fatalf("error is expected")

+	}

+}

@@ -11,7 +11,16 @@ import (

 // Size walks a directory tree and returns its total size in bytes.

 func Size(dir string) (size int64, err error) {

 	data := make(map[uint64]struct{})

-	err = filepath.Walk(dir, func(d string, fileInfo os.FileInfo, e error) error {

+	err = filepath.Walk(dir, func(d string, fileInfo os.FileInfo, err error) error {

+		if err != nil {

+			// if dir does not exist, Size() returns the error.

+			// if dir/x disappeared while walking, Size() ignores dir/x.

+			if os.IsNotExist(err) && d != dir {

+				return nil

+			}

+			return err

+		}

+

 		// Ignore directory sizes

 		if fileInfo == nil {

 			return nil

@@ -9,7 +9,16 @@ import (

 // Size walks a directory tree and returns its total size in bytes.

 func Size(dir string) (size int64, err error) {

-	err = filepath.Walk(dir, func(d string, fileInfo os.FileInfo, e error) error {

+	err = filepath.Walk(dir, func(d string, fileInfo os.FileInfo, err error) error {

+		if err != nil {

+			// if dir does not exist, Size() returns the error.

+			// if dir/x disappeared while walking, Size() ignores dir/x.

+			if os.IsNotExist(err) && d != dir {

+				return nil

+			}

+			return err

+		}

+

 		// Ignore directory sizes

 		if fileInfo == nil {

 			return nil