coud encode/decode nil value

Author: fanweixiao

pkg/spec/encode.go

@@ -27,6 +27,11 @@ func writePVarUInt64Buffer(val uint64) ([]byte, error) {
 	return buf, err
 }
 
+// SetNil set nil value, means length=0 packet
+func (p *Packet) SetNil() {
+	p.valbuf = make([]byte, 0)
+}
+
 // SetUInt32 set UInt32 value
 func (p *Packet) SetUInt32(v uint32) error {
 	size := encoding.SizeOfPVarUInt32(v)

pkg/spec/tlv_test.go

@@ -46,13 +46,15 @@ func TestFromBytes(t *testing.T) {
 }
 
 func TestReadTag(t *testing.T) {
+	testReadTag(t, []byte{0xFF, 0x7F, 0x00}, 0, 18446744073709551615, 2)
 	testReadTag(t, []byte{0x03, 0x01, 0x02}, 0, 3, 1)
 	testReadTag(t, []byte{0xFF, 0x04, 0x01, 0x02}, 1, 4, 2)
 	testReadTag(t, []byte{0x81, 0x05, 0x01, 0x02}, 0, 133, 2)
 	testReadTag(t, []byte{0xFF, 0x81, 0x05, 0x01, 0x02}, 1, 133, 3)
 }
 
 func TestReadLength(t *testing.T) {
+	testReadLength(t, []byte{0xFF, 0x7F, 0x00}, 2, 0, 3)
 	testReadLength(t, []byte{0x03, 0x01, 0x02}, 1, 1, 2)
 	testReadLength(t, []byte{0xFF, 0x04, 0x02, 0x00, 0x00}, 2, 2, 3)
 	testReadLength(t, []byte{0x05, 0x81, 0x05, 0x00}, 1, 133, 3)

pkg/spec/typed_value_test.go

@@ -4,6 +4,26 @@ import (
 	"testing"
 )
 
+func TestV2Nil(t *testing.T) {
+	p, _ := NewPacket(18446744073709551487)
+	p.SetNil()
+
+	buf := compareBytes(t, p, []byte{0xFE, 0x7F, 0x00})
+
+	dp, _ := FromBytes(buf)
+	if dp.Tag != 18446744073709551487 {
+		t.Errorf("result.Tag=% X, expect.Tag=% X", dp.Tag, uint64(18446744073709551487))
+	}
+
+	if dp.Length != 0 {
+		t.Errorf("result.Length=%d, expect.Length=%v", dp.Length, 0)
+	}
+
+	if len(dp.valbuf) != 0 {
+		t.Errorf("result.len(valbuf)=%d, expect.len(valbuf)=%v", len(dp.valbuf), 0)
+	}
+}
+
 func TestV2UInt32(t *testing.T) {
 	testV2UInt32(t, 0x03, 6, []byte{0x03, 0x01, 0x06})
 	testV2UInt32(t, 0x06, 127, []byte{0x06, 0x02, 0x80, 0x7F})