fix: IsRecoverable should return false for wrapped unrecoverable

Author: lizhiquan

retry.go

@@ -283,8 +283,13 @@ func Unrecoverable(err error) error {
 
 // IsRecoverable checks if error is an instance of `unrecoverableError`
 func IsRecoverable(err error) bool {
+	return !errors.Is(err, unrecoverableError{})
+}
+
+// Adds support for errors.Is usage on unrecoverableError
+func (unrecoverableError) Is(err error) bool {
 	_, isUnrecoverable := err.(unrecoverableError)
-	return !isUnrecoverable
+	return isUnrecoverable
 }
 
 func unpackUnrecoverable(err error) error {

retry_test.go

@@ -503,3 +503,14 @@ func TestUnwrap(t *testing.T) {
 	assert.Error(t, err)
 	assert.Equal(t, testError, errors.Unwrap(err))
 }
+
+func TestIsRecoverable(t *testing.T) {
+	err := errors.New("err")
+	assert.True(t, IsRecoverable(err))
+
+	err = Unrecoverable(err)
+	assert.False(t, IsRecoverable(err))
+
+	err = fmt.Errorf("wrapping: %w", err)
+	assert.False(t, IsRecoverable(err))
+}