cleanup serial package

common/serial/serial.go

@@ -5,6 +5,7 @@ import (
 	"io"
 )
 
+// ReadUint16 reads first two bytes from the reader, and then coverts them to an uint16 value.
 func ReadUint16(reader io.Reader) (uint16, error) {
 	var b [2]byte
 	if _, err := io.ReadFull(reader, b[:]); err != nil {
@@ -13,18 +14,21 @@ func ReadUint16(reader io.Reader) (uint16, error) {
 	return binary.BigEndian.Uint16(b[:]), nil
 }
 
+// WriteUint16 writes an uint16 value into writer.
 func WriteUint16(writer io.Writer, value uint16) (int, error) {
 	var b [2]byte
 	binary.BigEndian.PutUint16(b[:], value)
 	return writer.Write(b[:])
 }
 
+// WriteUint32 writes an uint32 value into writer.
 func WriteUint32(writer io.Writer, value uint32) (int, error) {
 	var b [4]byte
 	binary.BigEndian.PutUint32(b[:], value)
 	return writer.Write(b[:])
 }
 
+// WriteUint64 writes an uint64 value into writer.
 func WriteUint64(writer io.Writer, value uint64) (int, error) {
 	var b [8]byte
 	binary.BigEndian.PutUint64(b[:], value)

common/serial/string.go

@@ -25,6 +25,7 @@ func ToString(v interface{}) string {
 	}
 }
 
+// Concat concatenates all input into a single string.
 func Concat(v ...interface{}) string {
 	builder := strings.Builder{}
 	for _, value := range v {
@@ -32,9 +33,3 @@ func Concat(v ...interface{}) string {
 	}
 	return builder.String()
 }
-
-func WriteString(s string) func([]byte) (int, error) {
-	return func(b []byte) (int, error) {
-		return copy(b, []byte(s)), nil
-	}
-}

common/serial/typed_message.go

@@ -7,6 +7,7 @@ import (
 	"github.com/golang/protobuf/proto"
 )
 
+// ToTypeMessage converts a proto Message into TypedMessage.
 func ToTypedMessage(message proto.Message) *TypedMessage {
 	if message == nil {
 		return nil
@@ -18,10 +19,12 @@ func ToTypedMessage(message proto.Message) *TypedMessage {
 	}
 }
 
+// GetMessageType returns the name of this proto Message.
 func GetMessageType(message proto.Message) string {
 	return proto.MessageName(message)
 }
 
+// GetInstance creates a new instance of the message with messageType.
 func GetInstance(messageType string) (interface{}, error) {
 	mType := proto.MessageType(messageType)
 	if mType == nil || mType.Elem() == nil {
@@ -30,6 +33,7 @@ func GetInstance(messageType string) (interface{}, error) {
 	return reflect.New(mType.Elem()).Interface(), nil
 }
 
+// GetInstance converts current TypedMessage into a proto Message.
 func (v *TypedMessage) GetInstance() (proto.Message, error) {
 	instance, err := GetInstance(v.Type)
 	if err != nil {

common/serial/typed_message_test.go

@@ -14,3 +14,10 @@ func TestGetInstance(t *testing.T) {
 	assert(p, IsNil)
 	assert(err, IsNotNil)
 }
+
+func TestConvertingNilMessage(t *testing.T) {
+	x := ToTypedMessage(nil)
+	if x != nil {
+		t.Error("expect nil, but actually not")
+	}
+}