Merge pull request #26 from srvc/izumin5210/slice

Check error comparability for avoiding panic

Author: creasty

pkgerrors.go

@@ -1,6 +1,7 @@
 package fail
 
 import (
+	"reflect"
 	"strings"
 
 	pkgerrors "github.com/pkg/errors"
@@ -79,8 +80,15 @@ func extractPkgError(err error) *pkgError {
 		break
 	}
 
-	if len(stackTraces) == 0 && rootErr == err {
-		return nil
+	if len(stackTraces) == 0 {
+		ret, et := reflect.TypeOf(rootErr), reflect.TypeOf(err)
+		if ret != nil && et != nil && ret.Comparable() && et.Comparable() {
+			if rootErr == err {
+				return nil
+			}
+		} else {
+			return nil
+		}
 	}
 
 	// Extract annotated messages by removing the trailing message.

pkgerrors_test.go

@@ -2,6 +2,7 @@ package fail
 
 import (
 	"errors"
+	"strings"
 	"testing"
 
 	pkgerrors "github.com/pkg/errors"
@@ -20,6 +21,13 @@ func TestExtractPkgError(t *testing.T) {
 		assert.Nil(t, pkgErr)
 	})
 
+	t.Run("slice error", func(t *testing.T) {
+		err := errorSlice{errors.New("error")}
+
+		pkgErr := extractPkgError(err)
+		assert.Nil(t, pkgErr)
+	})
+
 	t.Run("pkg/errors.New", func(t *testing.T) {
 		err := pkgErrorsNew("message")
 
@@ -84,6 +92,16 @@ func TestExtractPkgError(t *testing.T) {
 			assert.NotEmpty(t, pkgErr.StackTrace)
 			assert.Equal(t, "pkgErrorsWrap", pkgErr.StackTrace[0].Func)
 		})
+
+		t.Run("with slice error", func(t *testing.T) {
+			err0 := errorSlice{errors.New("error")}
+			err1 := pkgErrorsWrap(err0, "message")
+
+			pkgErr := extractPkgError(err1)
+			assert.NotNil(t, pkgErr)
+			assert.Equal(t, err0, pkgErr.Err)
+			assert.NotEmpty(t, pkgErr.StackTrace)
+		})
 	})
 
 	t.Run("pkg/errors.WithMessage", func(t *testing.T) {
@@ -156,3 +174,13 @@ func pkgErrorsNew(msg string) error {
 func pkgErrorsWrap(err error, msg string) error {
 	return pkgerrors.Wrap(err, msg)
 }
+
+type errorSlice []error
+
+func (s errorSlice) Error() string {
+	msg := make([]string, len(s))
+	for i, e := range s {
+		msg[i] = e.Error()
+	}
+	return strings.Join(msg, ": ")
+}