return "json: invalid UTF-8 in string: " + strconv.Quote(e.S)
}

// A MarshalerError represents an error from calling a
// [Marshaler.MarshalJSON] or [encoding.TextMarshaler.MarshalText] method.
type MarshalerError struct {
	Type       reflect.Type
	Err        error
	sourceFunc string
}

func (e *MarshalerError) Error() string {
	srcFunc := e.sourceFunc
	if srcFunc == "" {
		srcFunc = "MarshalJSON"

	const errText = "json: test error"

	tests := []struct {
		CaseName
		err  *MarshalerError
		want string
	}{{
		Name(""),
		&MarshalerError{st, fmt.Errorf(errText), ""},
		"json: error calling MarshalJSON for type " + st.String() + ": " + errText,
	}, {
		Name(""),
		&MarshalerError{st, fmt.Errorf(errText), "TestMarshalerError"},