Only include verbose error if different

zapcore/field.go

@@ -152,12 +152,16 @@ func (f Field) AddTo(enc ObjectEncoder) {
 		enc.AddString(f.Key, f.Interface.(fmt.Stringer).String())
 	case ErrorType:
 		val := f.Interface.(error)
+		basic := val.Error()
+		enc.AddString(f.Key, basic)
 		if fancy, ok := val.(fmt.Formatter); ok {
-			// This is a rich error type, like those produced by
-			// github.com/pkg/errors.
-			enc.AddString(f.Key+"Verbose", fmt.Sprintf("%+v", fancy))
+			verbose := fmt.Sprintf("%+v", fancy)
+			if verbose != basic {
+				// This is a rich error type, like those produced by
+				// github.com/pkg/errors.
+				enc.AddString(f.Key+"Verbose", verbose)
+			}
 		}
-		enc.AddString(f.Key, val.Error())
 	case SkipType:
 		break
 	default:

zapcore/field_test.go

@@ -23,6 +23,7 @@ package zapcore_test
 import (
 	"errors"
 	"fmt"
+	"io"
 	"math"
 	"testing"
 	"time"
@@ -36,11 +37,19 @@ import (
 type users int
 
 func (u users) String() string {
-	return fmt.Sprintf("%d users", u)
+	return fmt.Sprintf("%d users", int(u))
 }
 
 func (u users) Error() string {
-	return fmt.Sprintf("%d too many users", u)
+	return fmt.Sprintf("%d too many users", int(u))
+}
+
+func (u users) Format(s fmt.State, verb rune) {
+	// Implement fmt.Formatter, but don't add any information beyond the basic
+	// Error method.
+	if verb == 'v' && s.Flag('+') {
+		io.WriteString(s, u.Error())
+	}
 }
 
 func (u users) MarshalLogObject(enc ObjectEncoder) error {