Fix negative number hex formatting and add JSON number formatting option

Signed-off-by: Peter Broadhurst <[email protected]>

pkg/abi/outputserialization.go

@@ -110,7 +110,16 @@ func Base10StringIntSerializer(i *big.Int) interface{} {
 }
 
 func HexIntSerializer0xPrefix(i *big.Int) interface{} {
-	return "0x" + i.Text(16)
+	absHi := new(big.Int).Abs(i)
+	sign := ""
+	if i.Sign() < 0 {
+		sign = "-"
+	}
+	return fmt.Sprintf("%s0x%s", sign, absHi.Text(16))
+}
+
+func JSONNumberIntSerializer(i *big.Int) interface{} {
+	return json.Number(i.String())
 }
 
 func Base10StringFloatSerializer(f *big.Float) interface{} {

pkg/abi/outputserialization_test.go

@@ -111,6 +111,40 @@ func TestJSONSerializationFormatsTuple(t *testing.T) {
 	]`, string(j3))
 }
 
+func TestJSONSerializationNumbers(t *testing.T) {
+
+	abi := testABI(t, sampleABI1)
+	assert.NotNil(t, abi)
+
+	v, err := (ParameterArray{{Type: "uint"}, {Type: "int"}}).ParseJSON([]byte(`[
+	   "123000000000000000000000112233",
+	   "-0x18d6f3720c92d9d437801b669"
+	]`))
+	assert.NoError(t, err)
+
+	j, err := v.JSON()
+	assert.NoError(t, err)
+	assert.JSONEq(t, `{
+	   "0": "123000000000000000000000112233",
+	   "1": "-123000000000000000000000112233"
+	}`, string(j))
+
+	j, err = NewSerializer().SetIntSerializer(HexIntSerializer0xPrefix).SerializeJSON(v)
+	assert.NoError(t, err)
+	assert.JSONEq(t, `{
+	   "0": "0x18d6f3720c92d9d437801b669",
+	   "1": "-0x18d6f3720c92d9d437801b669"
+	}`, string(j))
+
+	j, err = NewSerializer().SetIntSerializer(JSONNumberIntSerializer).SerializeJSON(v)
+	assert.NoError(t, err)
+	assert.JSONEq(t, `{
+	   "0": 123000000000000000000000112233,
+	   "1": -123000000000000000000000112233
+	}`, string(j))
+
+}
+
 func TestJSONSerializationForTypes(t *testing.T) {
 
 	abi := testABI(t, sampleABI2)