utils: BigInt now uses big.Int as embedded struct. Validation unittest.

utils/utils.go

@@ -136,12 +136,21 @@ func AskPassword(question string) (password string, err error) {
 }
 
 // BigInt is used by swagger as a big.Int type with Validate() function
-type BigInt big.Int
+type BigInt struct {
+	*big.Int
+}
 
-// Validate only checks that the number is >=0
+// Validate is an exported function that swagger uses.
+// However, the implementation does not need 'formats', so it is broken
+// out into validate().
 func (b *BigInt) Validate(formats strfmt.Registry) error {
+	return b.validate()
+}
+
+// validate checks that the number is >=0
+func (b *BigInt) validate() error {
 	var zero big.Int
-	var convertedCustomBigInt = big.Int(*b)
+	var convertedCustomBigInt = b
 
 	if convertedCustomBigInt.Cmp(&zero) != 1 {
 		return errors.New("swagger deserialization: Balance Validation failed")

utils/utils_test.go

@@ -0,0 +1,31 @@
+package utils
+
+import (
+	"errors"
+	"math"
+	"math/big"
+	"reflect"
+	"testing"
+)
+
+func TestValidate(t *testing.T) {
+	var amount = BigInt{&big.Int{}}
+	var tests = []struct {
+		input    int64
+		expected error
+	}{
+		{math.MinInt64, errors.New("the error message is not important")},
+		{-1, errors.New("the error message is not important")},
+		{0, errors.New("the error message is not important")},
+		{1, nil},
+		{math.MaxInt64, nil},
+	}
+
+	for _, test := range tests {
+		amount.SetInt64(test.input)
+		err := amount.validate()
+		if reflect.TypeOf(err) != reflect.TypeOf(test.expected) {
+			t.Errorf("Test Failed: %v inputted, %v expected, %#v received", test.input, test.expected, err)
+		}
+	}
+}