diff --git a/file_test.go b/file_test.go
index 47eae50..e346f10 100644
--- a/file_test.go
+++ b/file_test.go
@@ -228,5 +228,5 @@ func TestFile_ListDirInfoRecursiveContext(t *testing.T) {
 
 func TestFile_String(t *testing.T) {
 	path := filepath.Join("dir", "file.ext")
-	require.Equal(t, "local file system: "+path, File(path).String())
+	require.Equal(t, path+" (local file system)", File(path).String())
 }
diff --git a/memfile.go b/memfile.go
index 2d9fe98..5bf62fd 100644
--- a/memfile.go
+++ b/memfile.go
@@ -251,6 +251,22 @@ func (f MemFile) ReadJSON(ctx context.Context, output any) error {
 	return json.Unmarshal(f.FileData, output)
 }
 
+// WriteJSON mashalles input to JSON and writes it as the file.
+// Any indent arguments will be concanated and used as JSON line indentation.
+func (f *MemFile) WriteJSON(ctx context.Context, input any, indent ...string) (err error) {
+	var data []byte
+	if len(indent) == 0 {
+		data, err = json.Marshal(input)
+	} else {
+		data, err = json.MarshalIndent(input, "", strings.Join(indent, ""))
+	}
+	if err != nil {
+		return err
+	}
+	f.FileData = data
+	return nil
+}
+
 // ReadXML reads and unmarshalles the XML content of the file to output.
 func (f MemFile) ReadXML(ctx context.Context, output any) error {
 	if ctx.Err() != nil {
@@ -259,6 +275,22 @@ func (f MemFile) ReadXML(ctx context.Context, output any) error {
 	return xml.Unmarshal(f.FileData, output)
 }
 
+// WriteXML mashalles input to XML and writes it as the file.
+// Any indent arguments will be concanated and used as XML line indentation.
+func (f *MemFile) WriteXML(ctx context.Context, input any, indent ...string) (err error) {
+	var data []byte
+	if len(indent) == 0 {
+		data, err = xml.Marshal(input)
+	} else {
+		data, err = xml.MarshalIndent(input, "", strings.Join(indent, ""))
+	}
+	if err != nil {
+		return err
+	}
+	f.FileData = append([]byte(xml.Header), data...)
+	return nil
+}
+
 // // MarshalJSON implements the json.Marshaler interface
 // func (f MemFile) MarshalJSON() ([]byte, error) {
 // 	encodedData := base64.RawURLEncoding.EncodeToString(f.FileData)