feat: add stringer into rule coder

codes.go

@@ -1,14 +1,19 @@
 package goval
 
+import "fmt"
+
 type ruleCode int
 
 func (r ruleCode) Equal(other RuleCoder) bool {
 	v, ok := other.(ruleCode)
 	return ok && r == v
 }
 
+func (r ruleCode) String() string { return fmt.Sprintf("%d", r) }
+
 type RuleCoder interface {
 	Equal(other RuleCoder) bool
+	fmt.Stringer
 }
 
 const (

codes_test.go

@@ -11,13 +11,17 @@ func (c customTypeButSameBase) Equal(other RuleCoder) bool {
 	return ok && v == c
 }
 
+func (c customTypeButSameBase) String() string { return ruleCode(c).String() }
+
 type customTypeButSameRootBase int
 
 func (c customTypeButSameRootBase) Equal(other RuleCoder) bool {
 	v, ok := other.(customTypeButSameRootBase)
 	return ok && v == c
 }
 
+func (c customTypeButSameRootBase) String() string { return ruleCode(c).String() }
+
 func TestRuleCode_Equal(t *testing.T) {
 	tests := []struct {
 		desc string

errtrans/errtrans_test.go

@@ -2,9 +2,10 @@ package errtrans
 
 import (
 	"context"
-	"github.com/pkg-id/goval"
 	"strings"
 	"testing"
+
+	"github.com/pkg-id/goval"
 )
 
 type ruleCode bool
@@ -13,6 +14,8 @@ func (r ruleCode) Equal(_ goval.RuleCoder) bool {
 	return bool(r)
 }
 
+func (r ruleCode) String() string { return "ruleCode" }
+
 func TestTranslator_Translate(t *testing.T) {
 	ctx := context.Background()
 	bundle, _ := DefaultBundle()

goval_test.go

@@ -139,7 +139,7 @@ func TestExecute(t *testing.T) {
 			goval.Bind[int](8, goval.Number[int]().Required().With(customValidator)),
 		)
 
-		if err != internalError {
+		if !errors.Is(err, internalError) {
 			t.Fatalf("expect validation error is discarded and internal error is returned; but got %v", err)
 		}
 	})