Merge pull request #5 from stasundr/wei_converter

Fix convert to wei function. Now without lost precision

decimal.go

@@ -198,6 +198,10 @@ func (d *Decimal) GetMantissa() uint8 {
 }
 
 func (d *Decimal) FromString(value string) bool {
+	if d == nil {
+		*d = *NewDecimalZero()
+	}
+
 	if value == "" {
 		d.value = uint256.NewInt(0)
 		return true
@@ -266,6 +270,10 @@ func (d *Decimal) Rescale(mantissa uint8) *Decimal {
 }
 
 func (d *Decimal) ToBig() *big.Int {
+	if d.value == nil {
+		d.value = uint256.NewInt(0)
+	}
+
 	return d.value.ToBig()
 }
 

wei.go

@@ -4,10 +4,11 @@ import (
 	"math/big"
 )
 
+// ConvertToWei deprecated. Instead of ConvertToWei just use decimal.ToBig()
 func ConvertToWei(dec *Decimal, mantissa uint8) *big.Int {
 	if dec == nil || dec.value == nil {
 		return new(big.Int).SetUint64(0)
 	}
 
-	return NewDecimal(dec).Rescale(mantissa).ToBig()
+	return NewDecimal(dec).ToBig()
 }

wei_test.go

@@ -0,0 +1,46 @@
+package decimal
+
+import (
+	"github.com/stretchr/testify/assert"
+	"math/big"
+	"testing"
+)
+
+func TestConvertToWei(t *testing.T) {
+	d, ok := NewDecimalFromString("1")
+	assert.True(t, ok)
+	assert.Equal(t, ConvertToWei(d, 0), new(big.Int).SetUint64(1))
+
+	d, ok = NewDecimalFromString("1")
+	assert.True(t, ok)
+	assert.Equal(t, ConvertToWei(d, 10), new(big.Int).SetUint64(1))
+
+	d, ok = NewDecimalFromString("999999999999999999")
+	assert.True(t, ok)
+	assert.Equal(t, ConvertToWei(d, 10), new(big.Int).SetUint64(999999999999999999))
+
+	d, ok = NewDecimalFromString("115792089237316195423570985008687907853269984665640564039457584007913129639935")
+	assert.True(t, ok)
+	expected, ok := new(big.Int).SetString("115792089237316195423570985008687907853269984665640564039457584007913129639935", 10)
+	assert.Equal(t, ConvertToWei(d, 0), expected)
+
+	d, ok = NewDecimalFromString("115792089237316195423570985008687907853269984665640564039457584007913129639935")
+	assert.True(t, ok)
+	expected, ok = new(big.Int).SetString("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff", 16)
+	assert.Equal(t, ConvertToWei(d, 0), expected)
+
+	d, ok = NewDecimalFromString("10.10001")
+	assert.True(t, ok)
+	expected, ok = new(big.Int).SetString("1010001", 10)
+	assert.Equal(t, ConvertToWei(d, 0), expected)
+
+	d, ok = NewDecimalFromString("10.10001111111999999999901")
+	assert.True(t, ok)
+	expected, ok = new(big.Int).SetString("1010001111111999999999901", 10)
+	assert.Equal(t, ConvertToWei(d, 0), expected)
+
+	d, ok = NewDecimalFromString("10.1000111111199999999990112312313123123123")
+	assert.True(t, ok)
+	expected, ok = new(big.Int).SetString("101000111111199999999990112312313123123123", 10)
+	assert.Equal(t, ConvertToWei(d, 0), expected)
+}