Add MsgPack Marshal and Unmarshal Test Case

decimal_magpack_test.go

@@ -0,0 +1,55 @@
+package decimal
+
+import (
+	"testing"
+)
+
+func TestMsgPack(t *testing.T) {
+	for _, x := range testTable {
+		s := x.short
+		 // limit to 31 digits
+		if len(s) > 31 {
+			s = s[:31]
+			if s[30] == '.' {
+				s = s[:30]
+			}
+		}
+
+		// Prepare Test Decimal Data
+		amount, err := NewFromString(s)
+		if err != nil{
+			t.Error(err)
+		}
+		s = amount.String()
+
+		// MarshalMsg
+		var b []byte
+	 	out, err := amount.MarshalMsg(b)
+		if err != nil{
+			t.Errorf("error marshalMsg %s: %v", s, err)
+		}
+
+		// check msg type
+		typ := out[0] & 0xe0
+		if typ != 0xa0 {
+			t.Errorf("error marshalMsg, expected type = %b, got %b", 0xa0, typ)
+		}
+
+		// check msg len
+		sz := int(out[0] & 0x1f)
+		if sz != len(s) {
+			t.Errorf("error marshalMsg, expected size = %d, got %d", len(s), sz)
+		}
+
+		// UnmarshalMsg
+		var unmarshalAmount Decimal
+		_, err = unmarshalAmount.UnmarshalMsg(out)
+		if err != nil{
+			t.Errorf("error unmarshalMsg %s: %v", s, err)
+		}else if !unmarshalAmount.Equal(amount) {
+				t.Errorf("expected %s, got %s (%s, %d)",
+					amount.String(), unmarshalAmount.String(),
+					unmarshalAmount.value.String(), unmarshalAmount.exp)
+		}
+	}
+}

decimal_msgpack.go

@@ -9,17 +9,18 @@ var (
 )
 
 // MarshalMsg implements msgp.Marshaler
+//  Note: limit to 31 digits, if d.IntPart size large than 31, will be lose.
 func (d Decimal) MarshalMsg(b []byte) (o []byte, err error) {
 	o = require(b, d.Msgsize())
 	str := d.String()
 	sz := len(str)
-	// limit to 30 digits
-	// note, if d.IntPart size large than 30, will be lose.
-	if sz > 30 {
+	// limit to 31 digits
+	// note, if d.IntPart size large than 31, will be lose.
+	if sz > 31 {
+		sz = 31
+		// if last char is '.' then limit to 30 digits
+		if str[30] == '.' {
 			sz = 30
-		// if last char is '.' then limit to 20 digits
-		if str[29] == '.' {
-			sz = 29
 		}
 
 		str = str[:sz]